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Sample records for anhydride cured dgeba

  1. ULTRASONIC BEHAVIOR OF EPOXY RESINS/POLY (ETHYLENE OXIDE)BLENDS CURED WITH PHTHALIC ANHYDRIDE

    Institute of Scientific and Technical Information of China (English)

    ZHENG Sixun; WANG Haiqian; LUO Xiaolie; ZHANG Naibin; MA Dezhu; ZHU Changfei; HU Jiankai

    1995-01-01

    By means of ultrasonic attenuation apparatus, the ultrasonic velocity and attenuation of anhydride-cured epoxy resins (EP)/poly(ethylene oxide)(PEO)blends were measured on the basis of pulse-echo method. It was found that the sonic velocity of the blends decreased as the temperature increased, but attenuation coefficient increased and possessed a peak value. Larger velocity and smaller attenuation coefficient(α)can be obtained from perfect crosslinking network structures of pure DGEBA cured with phthalic anhydride (PA). As for cured DGEBA/PEO blend systems,sonic velocity decreased as a function of PEO concentration,but attenuation coefficient (α) increased.

  2. Curing behaviors and properties of an extrinsic toughened epoxy/anhydride system and an intrinsic toughened epoxy/anhydride system

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Mengjin; Liu, Jialin; Li, Xiangyuan [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Cheng, Jue, E-mail: chengjue@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Zhang, Junying, E-mail: zjybuct@gmail.com [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China)

    2013-02-20

    Highlights: ► Two curing systems (ETRS and ITRS) with similar chemical composite were prepared. ► The curing kinetics of the ETRS and the novel ITRS were comparatively studied. ► Crosslinking density can affect the kinetic schemes of the two curing systems. ► Their mechanical properties and thermal stabilities were also comparatively studied. ► Crosslinking density may play an influential role in mechanical properties. - Abstract: The curing kinetics of an extrinsic toughened epoxy (mixture of diglycidyl ether of bisphenol-A and 1,4-butanediol epoxy resin, DGEBA/DGEBD) and an intrinsic toughened epoxy (ethoxylated bisphenol-A epoxy resin with two oxyethylene units, DGEBAEO-2) using hexahydrophthalic anhydride (HHPA) as curing agent and tris-(dimethylaminomethyl) phenol (DMP-30) as accelerator were comparatively studied by non-isothermal DSC with a model-fitting Málek approach and a model-free advanced isoconversional method of Vyazovkin. The dynamic mechanical properties and thermal stabilities of the cured materials were investigated by DMTA and TGA, respectively. The results showed that Šesták–Berggren model can generally simulate well the reaction rates of these two systems. The activation energy of DGEBA/DGEBD/HHPA/DMP-30 at high fractional conversion changed much higher than that of DGEBAEO-2/HHPA/DMP-30, indicating the increased steric hindrance mainly affected the reaction kinetic scheme of DGEBA/DGEBD/HHPA/DMP-30. The T{sub g} and storage moduli of cured DGEBAEO-2/HHPA/DMP-30 were lower than those of cured DGEBA/DGEBD/HHPA/DMP-30 according to DMTA while TGA showed that the thermal stabilities of these two cured systems were similar.

  3. Cure and mechanical behaviors of cycloaliphatic/DGEBA epoxy blend system using electron-beam technique

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.R.; Heo, G.Y.; Park, S.J. [Korea Research Institute of Chemical Technology, Taejeon (Korea)

    2002-05-01

    4-Vinyl-1- cyclohexene diepoxide (VCE)/ diglycidyl ether of bisphenol -A(DGEBA) epoxy blends with benzylquinoxalinium hexafluoroanti-monate were cured using an electron-beam technique. the effect of DGEBA content to VCE on cure behavior, thermal stabilities, and mechanical properties was investigated. The composition of VCE/DGEBA blend system varied within 100:0, 80:20, 60:40. 40:60 20:80, and 0:100wt%. The cure behavior and thermal stability of the cured specimens was monited by near-infrared spectroscopy and thermogravimetric analysis, respectively. Also, the critical stress intensity factor (K{sub 1C}) test of the cured specimens was performed to study the mechanical interfacial properties. As a result, the decreases of short side-chide structure and chain scission were observed in NIR measurements as the DGEBA content increases, resulting in varying the hydroxyl and carbonyl groups. And, the initial decomposition temperature (IDT), temperature of maximum weight loss (T{sub max}), and decomposition activation energy (E{sub d}) as thermal stability factors were increased with increasing the DGEBA content. These results could be explained by mean of decreasing viscosity, stable aromatic ring structure, and grafted interpenetrating polymer network with increasing of DGEBA content. Also, the maximum K{sub 1C} value showed at mixing ratio of 40:60 wt% in this blend system. (author). 22 refs., 2 tabs., 6 figs.

  4. A Dielectric Study of the Time-Temperature-Transformation (TTT) Diagram of DGEBA Epoxy Resins Cured with DDS (Diaminodiphenylsulfone).

    Science.gov (United States)

    1983-12-14

    TRANSFORMATION (TTT) tDIAGRAM OF DGEBA EPOXY RESINS CURED WITH DDS by Norman F. Sheppard, Jr., Michael C. W. Coln and Stephen D. Senturia Article prepared for...DIAGRAM OF DGEBA EPOXY 6/83 - 12/83 RESINS CURED WITH DDS -6. PERFORMING ON*. REPORT NiJMUER ___________________________________Technical Report No. 7 7...Nicrodielectrometry, dielectric cure monitoring, time-temperature-transforma- tion diagram, epoxy resins, DGEBA , DDS, condictivity, permittivity, loss factor

  5. Cure Kinetics of DGEBA with Hyperbranched Poly(3-hydroxyphenyl) Phosphate as Curing Agent Studied by Non-isothermal DSC

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The cure kinetics of diglycidyl ether of bisphenol A(DGEBA) with hyperbranched poly(3-hydroxyphenyl) phosphate(HHPP) as the curing agent was investigated by means of non-isothermal differential scanning calorimetry(DSC) at various heating rates. The results were compared with the corresponding results by using 1,3-dihydroxybenzene(DHB) as a model compound. The results show that HHPP can enhance the cure reaction of DGEBA, resulting in the decrease of the peak temperature of the curing curve as well as the decrease of the activation energy because of the flexible -P-O- groups in the backbone of HHPP. However, both the activation energy of the cured polymer and the peak temperature of the curing curve are increased with DHB as a curing agent. The cure kinetics of the DGEBA/HHPP system was calculated by using the isoconversional method given by Málek. It was found that the two-parameter autocatalytic model(esták-Berggren equation) is the most adequate one to describe the cure kinetics of the studied system at various heating rates. The obtained non-isothermal DSC curves from the experimental data show the results being accordant with those theoretically calculated.

  6. Cure kinetics and mechanical interfacial characteristics of zeolite/DGEBA composites

    Energy Technology Data Exchange (ETDEWEB)

    Park, Soo Jin; Kim, Young Mi [Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); Shin, Jae Sup [Chungbuk National Univ., Cheongju (Korea, Republic of)

    2003-10-15

    In this work, the zeolite/diglycidylether of bisphenol A(DGEBA) systems were investigated in terms of the cure kinetics and mechanical interfacial properties of the composites. The 4, 4-Diamino Diphenyl Methane(DDM) was used as a curing agent for epoxy. Two types of zeolite(PZ) were prepared with 15 and 35 wt% KOH treatments(15-BZ and 35-BZ, respectively) for 24 h, and their surface characteristics were studied by X-ray Photoelectron Spectroscopy (XPS) and X-Ray Diffraction (XRD). Cure kinetics of the composites were examined in the context of Differential Scanning Calorimetry(DSC), and mechanical interfacial properties were investigated in critical stress intensity factor(K{sub IC}) and critical strain energy release rate(G{sub IC}). In the results of XPS and XRD, sodium ion(Na) of zeolite was exchanged for potassium ion(K), resulting from the treatment of KOH. Also, Si{sub 2p}/A1{sub 2p} composition ratios of the treated zeolite were increased, which could be attributed to the weakening of A1-O bond in framework. Cure activation energy(E{sub a}) of 15-BZ composites was decreased, whereas K{sub IC} and G{sub IC} were increased, compared with those of the pure zeolite/DGEBA composites. It was probably accounted that the acidity of zeolite was increased by surface treatments and the cure reaction between zeolite and epoxy was influenced on the increased acidity of zeolite.

  7. Catalytic behavior of Sn/Bi metal powder in anhydride-based epoxy curing.

    Science.gov (United States)

    Jang, Keon-Soo; Eom, Yong-Sung; Moon, Jong-Tae; Oh, Yong-Soo; Nam, Jae-Do

    2009-12-01

    In this paper, we report the catalytic activity of the Sn/Bi alloy beads and its acceleration of the exothermic epoxy curing reactions in various thermal conditions and bead compositions. As being used as low-melting solder balls in electronic interconnection processes with various epoxy systems, it was found that the Sn/Bi beads substantially lowered the exothermic peak temperature of the diglycidyl ether of bisphenol A (DGEBA)/anhydride systems in up to ca. 140 degrees C depending on different types of anhydride curing agents. The catalytic activation of Sn/Bi powder was initiated with a small amount of Sn/Bi powder, for example, lowering ca. 50 degrees C of the exothermic peak temperature by adding only 0.1 vol% of Sn/Bi powder. The catalytic capability of the powder was increased by using smaller sized beads corresponding to larger catalytic surface area at the same volume fraction. Exhibiting a latent catalytic effect, the catalytic activity of Sn/Bi powder was remained latent at temperatures lower than 100 degrees C in isothermal conditions.

  8. Luminescence spectroscopy applied to a study of the curing process of diglycidyl-ether of bisphenol-A (DGEBA

    Directory of Open Access Journals (Sweden)

    Rita de Cássia Mendonça Sales

    2005-09-01

    Full Text Available This work involved the application of luminescence spectroscopy under steady-state conditions to study the curing process of the epoxy resin diglycidyl-ether of bisphenol-A (DGEBA using the curing agents 4,4'-diaminodiphenylmethane (DDM and 4,4'-diaminodiphenylsulfone (DDS. Two fluorescence methods were employed: the intrinsic method related to the polymeric matrix and the extrinsic method, using the molecular probe 9-anthroic acid (9-AA. Stoichiometric mixtures, with and without 9-AA, were heated to 120 °C at a 5 °C/min heating rate. These samples were then cured at 120 °C for a further 2 hours and allowed to cool to room temperature for 20 minutes. The results obtained by the two methods indicate that the cross-linking reaction can be monitored by analyzing the spectral changes of the emission bands of DGEBA, curing agents and 9-AA.

  9. Luminescence spectroscopy applied to a study of the curing process of diglycidyl-ether of bisphenol-A (DGEBA)

    OpenAIRE

    Rita de Cássia Mendonça Sales; Deborah Dibbern Brunelli

    2005-01-01

    This work involved the application of luminescence spectroscopy under steady-state conditions to study the curing process of the epoxy resin diglycidyl-ether of bisphenol-A (DGEBA) using the curing agents 4,4'-diaminodiphenylmethane (DDM) and 4,4'-diaminodiphenylsulfone (DDS). Two fluorescence methods were employed: the intrinsic method related to the polymeric matrix and the extrinsic method, using the molecular probe 9-anthroic acid (9-AA). Stoichiometric mixtures, with and without 9-AA, we...

  10. Synthesis and Characterisation of Polyamidoamine-cured DGEBA-siloxane Interpenetrating Polymer Network

    OpenAIRE

    T.V. Thanikai Velan; I. Mohd. Bilal

    2002-01-01

    A commercially viable polydimethylsiloxane(PDMS)diglyceryl ether of bisphenol-A (DGEBA)interpenetrating network from hydroxyl terminated PDMS and DGEBA was synthesised.Epoxy resin was thoroughly mixed with PDMS to get a prepolymer. The interpenetrating polymer network has better electrical and thermal characteristics with high impact resistance compared to the virgin epoxy system.

  11. Crosslinking of mixtures of DGEBA with 1,6-dioxaspiro[4,4]nonan-2,7-dione initiated by tertiary amines. Part IV. Effect of hydroxyl groups on initiation and curing kinetics

    OpenAIRE

    Fernández Francos, Xavier; Cook, Wayne D.; Serra Albet, Àngels; Ramis Juan, Xavier; Liang, Genhai G.; Salla Tarragó, José María

    2010-01-01

    The anionic homopolymerization of DGEBA epoxy resin and its anionic copolymerization with a bislactone was studied using two alternative tertiary amines, 1-methylimidazole (1MI) and dimethylaminopyridine (DMAP) as initiators. 1MI caused slower cure than DMAP in neat DGEBA and DGEBA-bislactone formulations. Studies of the influence of the hydroxyl concentration in the DGEBA oligomer on its homopolymerization explain descrepancies in the literature regarding the ability of these initiators to p...

  12. Synthesis and Characterisation of Polyamidoamine-cured DGEBA-siloxane Interpenetrating Polymer Network

    Directory of Open Access Journals (Sweden)

    T.V. Thanikai Velan

    2002-01-01

    Full Text Available A commercially viable polydimethylsiloxane(PDMSdiglyceryl ether of bisphenol-A (DGEBAinterpenetrating network from hydroxyl terminated PDMS and DGEBA was synthesised.Epoxy resin was thoroughly mixed with PDMS to get a prepolymer. The interpenetrating polymer network has better electrical and thermal characteristics with high impact resistance compared to the virgin epoxy system.

  13. Kinetic study by FTIR and DSC on the cationic curing of a DGEBA/{gamma}-valerolactone mixture with ytterbium triflate as an initiator

    Energy Technology Data Exchange (ETDEWEB)

    Arasa, M. [Departament de Quimica Analitica i Quimica Organica, Universitat Rovira i Virgili. C/Marcel.li Domingo s/n, 43007 Tarragona (Spain); Ramis, X. [Laboratori de Termodinamica, ETSEIB. Universitat Politecnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain)], E-mail: ramis@mmt.upc.edu; Salla, J.M. [Laboratori de Termodinamica, ETSEIB. Universitat Politecnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain); Mantecon, A.; Serra, A. [Departament de Quimica Analitica i Quimica Organica, Universitat Rovira i Virgili. C/Marcel.li Domingo s/n, 43007 Tarragona (Spain)

    2008-12-05

    A mixture of diglycidylether of bisphenol A (DGEBA) and {gamma}-valerolactone ({gamma}-VL) was cured in the presence of ytterbium triflate as an initiator to obtain poly(esther-ether) thermosets. The kinetics of the various elemental reactions, which take place during the curing process, was studied by means of isothermal curing in the FTIR spectrometer. The kinetic parameters were calculated by means of the isoconversional procedure and the best-fit kinetic model was determined with the so-called compensation effect (isokinetic relationship). The isothermal kinetic analysis was compared with that obtained by dynamic curing in DSC.

  14. Structure, thermal and fracture mechanical properties of benzoxazine-modified amine-cured DGEBA epoxy resins

    Directory of Open Access Journals (Sweden)

    2011-03-01

    Full Text Available First, traditional diamine hardeners of epoxy resins (EP were checked as potential accelerators for the benzoxazine (BOX homopolymerization. It was established that the acceleration effect depends on both the type and amount of the diamine compounds. In the follow-up work amine-curable diglycidyl ether bisphenol A (DGEBA type EP was modified with BOX keeping the EP/BOX ratio constant (75/25 wt.%. The amine hardeners, added in the EP in stoichiometric amounts, were of aliphatic and aromatic nature, viz. diethylenetriamine (DETA, 4,4'-diaminodiphenyl methane (DDM, and their 1/1 mixture. The thermal, viscoelastic, flexural and fracture mechanical properties of the EP/BOX hybrids were determined and compared to those of the reference EPs. Based on dynamic-mechanical thermal analysis and atomic force microscopy the formation of co-network between EP and BOX was concluded. Homopolymerized BOX was built in the network in nanoscaled inclusions and it was associated with internal antiplasticization. Incorporation of BOX improved the charring, enhanced the flexural modulus and strength, and reduced the glass transition of the parent EP. The fracture toughness and energy were not improved by hybridization with BOX.

  15. Complex Cure Kinetics of the Hydroxyl-Epoxide Reaction in DGEBA Epoxy Hardened with Diethanolamine

    Science.gov (United States)

    Ancipink, Windy; McCoy, John; Kropka, Jamie; Celina, Mathias

    The curing of a diglycidyl ether of bisphenol-A Epoxy (Epon 828) with diethanolamine (DEA) involves a fast amine-epoxide reaction followed by a slower hydroxyl-epoxide reaction. At curing temperatures below 100°C, the time scales of these two reactions are well separated, and the hydroxyl addition can be studied as an ''isolated'' reaction. The hydroxyl-epoxide reaction is of great interest due to the complex kinetics involved, which are brought about by competing reactions. The reaction kinetics are believed to be tertiary amine catalyzed and are well fit to a modified form of the Kamal-type equation. Here we study the complex long term reaction kinetics at various temperatures, by using isothermal modulated differential scanning calorimetry, micro calorimetry, and infrared spectroscopy. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  16. Effect of Hyperbranched Polyester on Modification of Epoxy Resins Cured with Anhydride

    Institute of Scientific and Technical Information of China (English)

    Xiu Xia WANG; Zhi Gang JIANG; Yi Feng ZHANG

    2006-01-01

    The synthesis and characterization of hyperbranched polyester (HBP) with different molecular weight are studied. The effect of HBP on the modification of epoxy resins cured with anhydride is mainly discussed. The characteristics of HBP and the morphologies of cured system are determined by nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC) and scanning electron microscope (SEM). The impact strength of cured system is detected and Fourier transform infrared (FTIR) measurements were used to pursue the curing process. The investigation shows that HBP can improve the toughness by forming copolymer networks between epoxy resins, HBP and anhydride. Moreover, when the molecular weight of HBP is 1342g/mol the toughening effect is the best, and the changes of toughness are small with the increase of molecular weight of HBP to 3500 g/mol.

  17. Effects of Amine and Anhydride Curing Agents on the VARTM Matrix Processing Properties

    Science.gov (United States)

    Grimsley, Brian W.; Hubert, Pascal; Song, Xiaolan; Cano, Roberto J.; Loos, Alfred C.; Pipes, R. Byron

    2002-01-01

    To ensure successful application of composite structure for aerospace vehicles, it is necessary to develop material systems that meet a variety of requirements. The industry has recently developed a number of low-viscosity epoxy resins to meet the processing requirements associated with vacuum assisted resin transfer molding (VARTM) of aerospace components. The curing kinetics and viscosity of two of these resins, an amine-cured epoxy system, Applied Poleramic, Inc. VR-56-4 1, and an anhydride-cured epoxy system, A.T.A.R.D. Laboratories SI-ZG-5A, have been characterized for application in the VARTM process. Simulations were carried out using the process model, COMPRO, to examine heat transfer, curing kinetics and viscosity for different panel thicknesses and cure cycles. Results of these simulations indicate that the two resins have significantly different curing behaviors and flow characteristics.

  18. The influence of tertiary amine accelerators on the curing behaviors of epoxy/anhydride systems

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Tao; Zhang, Chongfeng; Zhang, Junying, E-mail: zjybuct@gmail.com; Cheng, Jue

    2014-02-10

    Highlights: • The influences of two types of accelerators (BDMA and DMP-30) on curing reaction of DGEBF/MeHHPA systems were studied comparatively. • The activation energy and kinetic parameters of DGEBF/MeHHPA systems with accelerator content of 0.2 phr and 0.5 phr were calculated, respectively. • The dependence of autocatalytic and non-autocatalytic curing reaction on the loading of accelerators was discussed. • The non-catalytic curing reaction dominated absolutely in the curing process of DGEBF/MeHHPA systems when the accelerator contents were 0.2 phr. - Abstract: Accelerators have significant effects on the curing behaviors of epoxy/anhydride (diglycidyl ether of bisphenol-F/methylhexahydrophthalic anhydride, DGEBF/MeHHPA) systems. Non-isothermal DSC was used to investigate the influence of dimethyl benzylamine (BDMA, 0.2 phr/0.5 phr) and Tris-(dimethyl aminomethyl) phenol (DMP-30, 0.2 phr/0.5 phr) on the curing behaviors of DGEBF/MeHHPA systems, respectively. When the amount of accelerators was kept constant, the activation energy calculated by Kissinger method changed slightly in the presence of either BDMA or DMP-30. And, with increasing the accelerator content from 0.2 phr to 0.5 phr, the value of activation energy decreased from 115 kJ/mol to 85 kJ/mol. Furthermore, the calculation results of Málek method identified that all systems in this study fitted Sesták–Berggren (SB) model and the corresponding model parameters, m and n, were obtained. It was found that the contribution of autocatalytic reaction with low accelerator content (0.2 phr) was far less than that with high accelerator content (0.5 phr)

  19. Kinetic analysis by DSC of the cationic curing of mixtures of DGEBA and 6,6-dimethyl (4,8-dioxaspiro[2.5]octane-5,7-dione)

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, Lidia [Departament de Quimica Analitica i Quimica Organica, Universitat Rovira i Virgili, C/Marcelli Domingo s/n, 43007 Tarragona (Spain); Ramis, Xavier [Laboratori de Termodinamica, ETSEIB, Universitat Politecnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain); Salla, Josep Maria [Laboratori de Termodinamica, ETSEIB, Universitat Politecnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain)], E-mail: salla@mmt.upc.edu; Mantecon, Ana; Serra, Angels [Departament de Quimica Analitica i Quimica Organica, Universitat Rovira i Virgili, C/Marcelli Domingo s/n, 43007 Tarragona (Spain)

    2007-11-25

    The kinetics of the thermal cationic cure reaction of mixtures in different proportions of diglycidylether of bisphenol A (DGEBA) with 6,6-dimethyl (4,8-dioxaspiro[2.5]octane-5,7-dione) (MCP) initiated by ytterbium or lanthanum triflates or using a conventional initiator, BF{sub 3}.MEA was investigated. The non-isothermal differential scanning calorimetry (DSC) experiments at a controlled heating rate was used for obtaining the kinetic parameters of the reactive systems. BF{sub 3}.MEA and lanthanide triflates initiated curing systems follow a complete different kinetic model. Among lanthanide triflates, ytterbium is the most active initiator.

  20. MECHANICAL RELAXATION AND INTERMOLECULAR INTERACTION IN EPOXY RESINS/POLY (ETHYLENE OXIDE)BLENDS CURED WITH PHTHALIC ANHYDRIDE

    Institute of Scientific and Technical Information of China (English)

    LUO Xiaolie; ZHENG Sixun; MA Dezhu; HU Keliang

    1995-01-01

    The miscibility of the blend,composed of a bisphenol A epoxy resins (Diglycidyl etherof bisphenol A) (DGEBA) and poly(ethylene oxide) (PEO) and crosslinked by phthalicanhydride (PA) was studied using dynamic mechanical method. Single glass transitiontemperatures intermediate between the two pure components were observed for all blendlevels. The secondary relaxation mechanism should relate to not only diester linkage, butalso hydroxyether structural unit in the system. Fourier transform infrared spectroscopy(FTIR) is applied to study the curing reaction and intermolecular specific interaction of thesystem. The results indicate the PEO participates the crosslinking reaction, accelerates thecuring reaction and make the reaction more perfect. The shifts of the hydroxyl band andcarbonyl band demonstrate the presence of the intermolecular interaction in the curedblend. Moreover, the molecular interaction between the side hydroxyl in the hydroxyetherunits and the ether bond in PEO macromolecules is stronger.

  1. Characterization of the curing agents used in epoxy resins with TG/FT-IR technique

    OpenAIRE

    Benedita M. V. Romão; Diniz,Milton F.; Margarete F. P. Azevedo; Vera L. Lourenço; Luiz C. Pardini; Rita C.L. Dutra; Fabrice Burel

    2006-01-01

    Samples of epoxy resin (EP) based on the diglycidyl ether of bisphenol A (DGEBA), cured with nadic methyl anhydride (NMA) and mercaptan (CAPCURE 3-800), or amine-phenol (CAPCURE EH-30), respectively, SE 4 and SE 5, were prepared in the stoichiometric ratio determined by the supplier. The curing behaviour of the epoxy systems SE 4 and SE 5 was followed by DSC (Differential Scanning Calorimetry). These SE and their ingredients were analyzed using FTIR transmission techniques (KBr pellets, pyrol...

  2. Chain extension and branching of poly(L-lactic acid produced by reaction with a DGEBA-based epoxy resin

    Directory of Open Access Journals (Sweden)

    2007-11-01

    Full Text Available Dicarboxylated poly(L-lactic acid (PLLA was synthesized by reacting succinic anhydride with L-lactic acid prepolymer prepared by melt polycondensation. PLLA and epoxy resin based on diglycidyl ether of bisphenol A (DGEBA copolymers were prepared by chain extension of dicarboxylated PLLA with DGEBA. Infrared spectra confirmed the formation of dicarboxylated PLLA and PLLA/DGEBA copolymer. Influences of reaction temperature, reaction time, and the amount of DGEBA on the molecular weight and gel content of PLLA/DGEBA copolymer were studied. The viscosity average molecular weight of PLLA/DGEBA copolymer reached 87 900 when reaction temperature, reaction time, and mol ratio of dicarboxylated PLLA to DGEBA is 150°C, 30 min, and 1:1 respectively, while gel content of PLLA/DGEBA copolymer is almost zero.

  3. Mode I fracture toughness behavior of hydro-thermally aged carbon fibre reinforced DGEBA-HHPA-PES systems

    Science.gov (United States)

    Alessi, Sabina; Pitarresi, Giuseppe; Spadaro, Giuseppe; Tumino, Davide

    2012-07-01

    In this work the Mode I fracture toughness behavior of unidirectional CFRP laminates is investigated by means of Double Cantilever Beam (DCB) tests. The composite samples were manufactured by thermal curing after impregnation of a Carbon fabric with a DGEBA epoxy and anhydride HHPA curing agent. One resin batch was also mixed with a PES thermoplastic monomer to enhance the matrix toughness. Two lots of samples, toughened and untoughened, were then left to soak in hot water to achieve various degrees of aging. The influence of matrix toughening and hydrothermal aging on the delamination behavior of the composite have then been assessed and correlated with characterization data from Dynamic Mechanical Thermal Analysis (DMTA) and Scanning Electron Microscopy (SEM).

  4. Thermal curing of an epoxy-anhydride system modified with hyperbranched poly(ethylene imine)s with different terminal groups

    OpenAIRE

    Morancho Llena, José María; Fernández Francos, Xavier; Acebo Gorostiza, Cristina; Ramis Juan, Xavier; Salla Tarragó, José María; Serra Albet, Àngels

    2017-01-01

    New hyperbranched polymers (HBP) have been synthesized by reaction of a poly(ethylene imine) with phenyl and t-butyl isocyanates. These HBPs have been characterized by 1H-NMR (nuclear magnetic resonance of hydrogen) and Fourier transform infrared spectroscopy. Their influence on the curing and properties of epoxy-anhydride thermosets has been studied by different techniques: differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetry (TG). The ...

  5. Mechanical properties and biocompatibility of two polyepoxy matrices: DGEBA-DDM and DGEBA-IPD.

    Science.gov (United States)

    Berruet, R; Vinard, E; Calle, A; Tighzert, H L; Chabert, B; Magloire, H; Eloy, R

    1987-05-01

    The aim of this paper was to study the biocompatibility and mechanical properties of materials for orthopaedic and odontologic surgical use. The products used were obtained by polycondensation of a diepoxy resin (DGEBA) with two curing agents (DDM or IPD). The materials present a slight swelling in liquid medium and their thermomechanical properties are hardly affected after 12 month implantation. The absence of molecular desorption in isotonic liquid and human serum confirms their hydrolytic stability and thus their inertia. These materials do not give rise to an intolerance reaction by neighbouring tissues during implantation time (1 d to 12 month).

  6. Study on Curing Reaction of Epoxidized Linseed Oil with Anhydrides%环氧亚麻油与酸酐固化反应研究

    Institute of Scientific and Technical Information of China (English)

    董宇; 裴帆; 石春韬; 王雪; 许艳玲; 李萍

    2015-01-01

    Epoxidized linseed oil is a type of epoxy resin synthesized by the epoxidation reaction of linsee d oil. Thermosetting epoxy resin-based polymer composites with a variety of properties can be prepared after the reaction of epoxy resin and curing agents, which can be used in many fields. In this work, the curing reaction of epoxidized linseed oil was studied and the optimized reaction conditions were also obtained by the application of orthogonal experimental method based on the best selection of curing agent and accelerator. Fourier transform infrared spectroscopy(FT-IR)and differential scanning calorimetry (DSC)techniques were applied to investigate the curing reaction process and characterization. The results show that a mixture of maleic anhydride and phthalic anhydride (molar ratio 0.83﹕0.17) was the best curing agent while N, N-dimethylbenzylamine was the best accelerator. The factors impacting curing reaction were in the order of mixed anhydride/epoxy ratio > temperature >amount of accelerator > time. Curing degree of the final product could reach 97.13% under the following optimized conditions:mixed anhydride / epoxy ratio was 1.2﹕1.0 (molar ratio), the amount of accelerator was 2.5%, the temperature and time were 120 ℃ and 4 h,respectively. IR characteristic absorption of epoxy and anhydride gradually disappeared as the proceeding of the reaction and the curing reaction tended to be complete. Curing reaction of epoxidized linseed oil with mixed anhydride is an exothermic one with peak temperature at 182.6 ℃ and reaction enthalpy is -130.2 J/g.%环氧亚麻油是亚麻油通过环氧化反应合成的环氧树脂,其可进一步与固化剂反应,制备具有多种性能的热固性环氧树脂基复合材料,在多种领域具有广泛应用。文中研究了环氧亚麻油的固化反应,在选择最佳固化剂和促进剂的基础上,用正交试验优化反应条件,红外光谱表征固化反应过程,差示扫描量热法(DSC

  7. Oligoesters and polyesters produced by the curing of sunflower oil epoxidized biodiesel with cis-cyclohexane dicarboxylic anhydride: Synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Reiznautt, Quelen B. [Laboratory of Instrumentation and Molecular Dynamics, Department of Physical Chemistry, Chemistry Institute, Federal University of Rio Grande do Sul, Av. Bento Goncalves 9500, CEP: 91501-970, Porto Alegre (Brazil); Garcia, Irene T.S. [Department of Analytical and Inorganic Chemistry, Chemistry and Geosciences Institute, Federal University of Pelotas, 96010-900, Pelotas (Brazil); Samios, Dimitrios, E-mail: dsamios@iq.ufrgs.br [Laboratory of Instrumentation and Molecular Dynamics, Department of Physical Chemistry, Chemistry Institute, Federal University of Rio Grande do Sul, Av. Bento Goncalves 9500, CEP: 91501-970, Porto Alegre (Brazil)

    2009-08-31

    Oligoesters and polyesters produced from sunflower oil biodiesel were synthesized and characterized. The polymers were obtained through the reaction of fatty acid methyl epoxy esters (EE) with cis-1,2-cyclohexane dicarboxylic anhydride (CH) and triethylamine (TEA) as initiator. Some reactions were conducted by adding small amounts of 1,4-butanediol diglycidyl ether (BDGE). The intermediate products of the synthesis process, including sunflower oil, methyl ester, epoxidised methyl esters, and the oligoesters and polyesters produced, were followed by Fourier Transform Infrared Spectroscopy and {sup 1}H and {sup 13}C nuclear magnetic resonance. The products obtained from the curing of the epoxidised esters with different compositions present similar chemical structures; however, they still depend on the amount of the epoxy resin BDGE that was added in the polymerization reaction. Thermoplastic materials with molecular weights (MW) starting at 3800 g/mol and reaching very high MWs, resulted in cross linked polymers. The thermal behaviour of the different products was investigated using differential scanning calorimetry and thermogravimetric analyses. The presence of BDGE in the structure of the materials increases the bonding capacity, resulting in higher molecular weight materials, which present good thermal stability.

  8. THE THERMAL AND ABLATIVE DEGRADATION OF SOME EPOXY RESINS CURED WITH METHYL BICYCLO(2.2.1)HEPTENE-2,3-DICARBOXYLIC ANHYDRIDE (NMA).

    Science.gov (United States)

    ABLATION), (* EPOXY RESINS , (*PYROLYSIS, EPOXY RESINS ), CYCLOALKENES, ANHYDRIDES, CATALYSTS, ADDITIVES, CROSSLINKING(CHEMISTRY), REACTION KINETICS, DEGRADATION, AGING(MATERIALS), INFRARED SPECTRA, CHROMATOGRAPHIC ANALYSIS.

  9. AFM and XRD characterization of silver nanoparticles films deposited on the surface of DGEBA epoxy resin by ion sputtering

    OpenAIRE

    José Elisandro de Andrade; Rogério Machado; Marcelo Andrade Macêdo; Frederico Guilherme Carvalho Cunha

    2013-01-01

    In this work, silver atoms were deposited by ion sputtering on the surface of diglycidyl ether of bisphenol A (DGEBA) epoxy resin cured at 150 °C for 6 hours in air. The films of DGEBA and its precursors were characterized by Raman spectroscopy to identify the main functional groups and their relationship with the deposited silver atoms. Silver thin films of 5, 10, 15 and 20 nm were deposited on the epoxy resin at room temperature. Both the initial film of DGEBA and the subsequent silver thin...

  10. Increasing the electrical discharge endurance of acid anhydride cured DGEBA epoxy resin by dispersion of nanoparticle silica. High Perform. Polym. 11 (1999) pp 281-296 by IOP Publishing Ltd

    DEFF Research Database (Denmark)

    Henk, Peter O; Kortsen, T.W.; Kvarts, T.

    1999-01-01

    combinations were used: (a) fumed nanoparticle silicon dioxide referred to as Aerosil, (b) equal volumes of Aerosil and nanoparticle anatase, and (c) Aerosil plus anatase in combination with coarse-particle filler grade calcium-magnesium carbonate dolomite. A test for endurance using the CIGRE method II...... the endurance by a factor of up to 20 as the Aerosil content goes from zero to 5.4 vol%. Aerosil mixed with anatase has a similar effect. The high level of endurance is maintained with an additional high-volume (35 vol.%) filling of coarse-particle dolomite to an epoxy system already containing Aerosil...

  11. Characterization of the curing agents used in epoxy resins with TG/FT-IR technique

    Directory of Open Access Journals (Sweden)

    Benedita M. V. Romão

    2006-06-01

    Full Text Available Samples of epoxy resin (EP based on the diglycidyl ether of bisphenol A (DGEBA, cured with nadic methyl anhydride (NMA and mercaptan (CAPCURE 3-800, or amine-phenol (CAPCURE EH-30, respectively, SE 4 and SE 5, were prepared in the stoichiometric ratio determined by the supplier. The curing behaviour of the epoxy systems SE 4 and SE 5 was followed by DSC (Differential Scanning Calorimetry. These SE and their ingredients were analyzed using FTIR transmission techniques (KBr pellets, pyrolysis without control and controlled pyrolysis-FT-IR, the CONTROLPIR/FT-IR for characterizing the curing agents (CA. The temperature range used for samples pyrolysis was found from TG (thermogravimetry. Thus, the FT-IR bands of liquid pyrolysate obtained by CONTROLPIR/FT-IR were evaluated, in comparison to the reference spectrum of CA. The characterization of CA was also possible, by the analysis of such SE with the TG/FT-IR technique.

  12. Molecular Modeling of Thermosetting Polymers: Effects of Degree of Curing and Chain Length on Thermo-Mechanical Properties

    Science.gov (United States)

    2012-08-01

    the mechanical properties of one particular thermosetting polymer, DGEBA /DETDA epoxy system using atomistic molecular dynamics simulations. A series...response of the DGEBA /DETDA epoxy system, the atomistic simulation part described below will only consider a DGEBA monomer as the resin...on the reaction of the DGEBA (diglycidyl ether of bisphenol A) monomers with curing agent EPI-Cure-W (diethylenetoluenediamine, DETDA) (Figure 2

  13. Curing Kinetics of DGEBA/Polyether Amine by Isothermal DSC%等温DSC法研究聚醚胺与环氧树脂固化反应动力学

    Institute of Scientific and Technical Information of China (English)

    孙文兵

    2010-01-01

    为了给环氧树脂(DGEBA)/聚醚胺(T403)的实际固化工艺提供指导,在等温条件下采用差示扫描量热法(DSC)对该体系固化过程进行了研究.运用Kenny图像分析法得到了动力学参数,建立了kamal动力学模型;在考虑扩散影响的基础上,多次运用非线性拟合法得到了扩散系数(C)和临界固化度(αc),进一步建立了带扩散控制的动力学模型.结果表明,总反应级数为2.04~2.40,且随固化温度升高而下降.固化反应的两个速率常数都随温度升高而增大,对应的表观活化能分别为42.99和54.23kJ/mol.研究发现不带扩散控制的动力学模型可以较好地描述固化过程的前期阶段,而带扩散控制的动力学模型则可以更好地描述固化全过程.随着固化温度升高,αc增大,扩散影响减小,而带扩散控制的动力学模型与实验结果符合得越好.固化过程属三分子反应,具有明显的自催化特征.

  14. New improved thermosets obtained from DGEBA and a hyperbranched poly(ester-amide)

    OpenAIRE

    Morell, Mireia; Ramis Juan, Xavier; Ferrando Piera, Francesc; Yu, Yingfeng; Serra Albet, Àngels

    2009-01-01

    The influence on the curing process of a commercial hydroxy-functionalized hyperbranched poly(ester-amide) (HBP) Hybrane® S1200 on diglycidylether of bisphenol A (DGEBA) was studied. By Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR) the curing reaction was studied and the covalent incorporation of the modifier in the matrix was proved. By Thermomechanical Analysis (TMA) the reduction of the contraction after gelation on changing the S1200 proportio...

  15. 亚临界水介质回收酸酐固化环氧树脂/碳纤维复合材料%Recycling of Carbon Fiber Reinforced Epoxy Resin Cured with Anhydride in Subcritical Water

    Institute of Scientific and Technical Information of China (English)

    王一明; 刘杰; 吴广峰; 唐涛

    2013-01-01

    研究了不同添加剂对碳纤维增强酸酐固化环氧树脂复合材料在亚临界水中降解的影响,通过IR、GC-MS等分析,确定了环氧树脂的分解机理主要为酯键的断裂.结果表明,KOH与苯酚对酸酐固化环氧树脂的分解没有协同效应,碱性物质更有利于酯键的断裂.甲基四氢邻苯二甲酸酐固化的环氧树脂增强碳纤维复合材料在反应温度为250℃、反应时间为60 min、KOH浓度为0.2 mol/L时可完全分解,回收碳纤维的拉伸强度和表面形貌未受影响.%Effect of additives on the decomposition behavior of the carbon fiber reinforced epoxy resin cured with anhydride in subcritical water was investigated.IR and GC-MS results show that the decomposition is ascribed to cleavage of ester bond.KOH and phenol does not exhibit the synergetic effect on the decomposition of anhydride cured epoxy resin.Alkaline conditions are found to be favorable to the cleavage of ester linkages.The carbon fiber reinforced methyl-tetrabydrophalic anhydride (MeTHPA) cured epoxy resin composite was totally decomposed with the addition of 0.2 mol/L KOH at 250 ℃ for 60 min.The tensile strength and morphology of the recycled carbon fibers are not influenced.

  16. Preparation of epoxy/zirconia hybrid materials via in situ polymerization using zirconium alkoxide coordinated with acid anhydride

    Energy Technology Data Exchange (ETDEWEB)

    Ochi, Mitsukazu, E-mail: mochi@ipcku.kansai-u.ac.jp [Faculty of Chemistry, Materials and Bioengineering, Kansai University, 3-3-35 Suita-shi, Osaka 564-8680 (Japan); Nii, Daisuke; Harada, Miyuki [Faculty of Chemistry, Materials and Bioengineering, Kansai University, 3-3-35 Suita-shi, Osaka 564-8680 (Japan)

    2011-09-15

    Highlights: {yields} Novel epoxy/zirconia hybrid materials were synthesized via in situ polymerization using zirconium alkoxide coordinated with acid anhydride. {yields} The half-ester compound of acid anhydride desorbed from zirconium played as curing agent of epoxy resin. {yields} The zirconia was uniformly dispersed in the epoxy matrix on the nanometer or sub-nanometer scale by synchronizing the epoxy curing and sol-gel reactions. {yields} The refractive indices of the hybrid materials significantly improved with an increase in the zirconia content. - Abstract: Novel epoxy/zirconia hybrid materials were synthesized using a bisphenol A epoxy resin (diglycidyl ether of bisphenol A; DGEBA), zirconium(IV)-n-propoxide (ZTNP), and hexahydrophthalic anhydride (HHPA) via in situ polymerization. HHPA played two roles in this system: it acted as a modifier to control the hydrolysis and condensation reactions of zirconium alkoxide and also as a curing agent - the half-ester compound of HHPA desorbed from zirconium reacted with the epoxy resin to form the epoxy network. As a result, both the sol-gel reaction and epoxy curing occurred simultaneously in a homogeneous solution, and organic-inorganic hybrid materials were readily obtained. Further, the zirconia produced by the in situ polymerization was uniformly dispersed in the epoxy matrix on the nanometer or sub-nanometer scale; thus, hybrid materials that exhibited excellent optical transparency were obtained. Furthermore, the heat resistance of the hybrid materials could be improved by hybridization with zirconia. And, the refractive indices of the hybrid materials significantly improved with an increase in the zirconia content.

  17. Curing mechanism and kinetics of epoxy/anhydride system modified by benzoxazine%苯并嗪改性环氧酸酐体系的固化机理及动力学

    Institute of Scientific and Technical Information of China (English)

    廖进彬; 姜其斌; 曾智; 李鸿岩

    2014-01-01

    An epoxy/anhydride system was modified by aromatic diamine-based benzoxazine. The curing mechanism of the system was analyzed with Fourier transform infrared spectroscopy(FT-IR)and differential scanning calorimetry (DSC). The blend system exhibited two curing reactions in the curing process. Epoxy resin first cured with sufficient anhydride catalyzed by imidazole at 100℃, and cured completely at 150℃ for 2 h. Benzoxazine underwent ring-opening polymerization at 180℃. The curing kinetics of modified resin system was studied with non-isothermal DSC at different heating rates. The average activation energies of two reactions were calculated utilizing the Flynn-Wall-Ozawa method to be 65.27 kJ·mol-1 and 92.8 kJ·mol-1, respectively. Both curing reactions were found to be autocatalytic processes by the Friedman method, and the predicted curves from the autocatalytic model fitted well with those of experiments.%利用一种二胺型苯并嗪改性环氧酸酐体系。通过FT-IR和DSC分析了改性体系的固化机理。结果表明:共混树脂体系在固化时存在两个反应,首先是环氧树脂与足量的酸酐在咪唑作用下在100℃先开始固化,并在150℃固化2 h后固化完全,之后苯并嗪在180℃发生开环聚合。用非等温DSC法研究了该共混体系的固化动力学。采用 Flynn-Wall-Ozawa 方法求出了共混体系在固化时两个固化反应的活化能,分别为65.27 kJ·mol-1和92.8 kJ·mol-1,并利用Friedman方法判断了两个反应都是自催化反应,计算得到自催化模型曲线与实验曲线能较好地吻合。

  18. Cationic concentration effects on electron beam cured of carbon-epoxy composites

    Science.gov (United States)

    Nishitsuji, D. A.; Marinucci, G.; Evora, M. C.; Silva, L. G. A.

    2010-03-01

    Electron beam (e-beam) curing is a technology that offers advantages over the thermal curing process, that usually requires high temperature and are time-consuming. E-beam curing is faster and occurs at low temperatures that help reduce residual mechanical stresses in a thermoset composite. The aim of the present study is to analyze the effects of cationic initiator (diaryliodonium hexafluoroantimonate) ranged from 1 to 3 wt% in DGEBA (diglycidyl ether of bisphenol A) epoxy resin when cured by a 1.5 MeV electron beam. The specimens were cured to a total dose of 200.4 kGy for 40 min. Analyses by dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC) show that the e-beam irradiated samples with 2 wt% cationic initiator were 96% cured obtained a glass transition temperature (tan δ) of 167 °C. The same epoxy resin, thermally cured for 16 h with an anhydride hardener, reached a Tg (tan δ) of 136 °C. So, the irradiated sample had its Tg increased approximately 20% and the curing process was much less time consuming.

  19. Cationic concentration effects on electron beam cured of carbon-epoxy composites

    Energy Technology Data Exchange (ETDEWEB)

    Nishitsuji, D.A., E-mail: delmo_amari@yahoo.com.b [Brazilian Navy Technological Center, Sao Paulo (Brazil); Marinucci, G. [Brazilian Navy Technological Center, Sao Paulo (Brazil); Energetic and Nuclear Research Institute-IPEN-CNEN/SP, Av. Prof. Lineu Prestes, 2242-Cidade Universitaria, 05508-000 Sao Paulo/SP (Brazil); Evora, M.C. [Institute of Advanced Studies/CTA, Sao Jose dos Campos/SP (Brazil); Silva, L.G.A. [Energetic and Nuclear Research Institute-IPEN-CNEN/SP, Av. Prof. Lineu Prestes, 2242-Cidade Universitaria, 05508-000 Sao Paulo/SP (Brazil)

    2010-03-15

    Electron beam (e-beam) curing is a technology that offers advantages over the thermal curing process, that usually requires high temperature and are time-consuming. E-beam curing is faster and occurs at low temperatures that help reduce residual mechanical stresses in a thermoset composite. The aim of the present study is to analyze the effects of cationic initiator (diaryliodonium hexafluoroantimonate) ranged from 1 to 3 wt% in DGEBA (diglycidyl ether of bisphenol A) epoxy resin when cured by a 1.5 MeV electron beam. The specimens were cured to a total dose of 200.4 kGy for 40 min. Analyses by dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC) show that the e-beam irradiated samples with 2 wt% cationic initiator were 96% cured obtained a glass transition temperature (tan delta) of 167 deg. C. The same epoxy resin, thermally cured for 16 h with an anhydride hardener, reached a T{sub g} (tan delta) of 136 deg. C. So, the irradiated sample had its T{sub g} increased approximately 20% and the curing process was much less time consuming.

  20. Adherend Surface Effects on Epoxy Cure by NMR

    Science.gov (United States)

    1994-05-11

    questions. 3 2. Summary of results. The structure and dynamics of the cure of the epoxy resin system based on the diglycidyl ether of bisphenol-A ( DGEBA ) is... DGEBA ), obtained from Dow Chemical Co. (der 332) was heated in the oven at temperature 160 OC until completely melted. The sample was cooled and at the...epoxy to ether conversion with the NMR analysis. (b) Results and Interpretation. The mixture of DGEBA with DDS was studied at temperature 1600C. The

  1. 桐马酸酐与环氧树脂的非等温固化反应动力学%Non - isothermal curing kinetics of Tung - maleic anhydride and epoxy resin

    Institute of Scientific and Technical Information of China (English)

    黄坤; 夏建陵; 李梅; 林贵福; 连建伟

    2011-01-01

    The non- isothermal curing kinetics of Tung- maleic anhydride and epoxy resin E-51 blend with 1%DMP -30 by weight was studied by Má1ek method. The real curing process was stimulated well using mechanism equation (S)esták - Berggren. The active energy calculated by iso - conversion ratio method was 69. 78 kJ/mol. The pre -exponential factor A was 4. 567 × 108 min -1 and the values of n and m were 1. 082 and O. 456, respectively.Based on the curing kinetic equation obtained, the calculated curing time of the system with 98% conversion rate was 115 minutes at the curing temperature 137. 05 ℃.%采用Málek法对桐马酸酐与双酚A环氧树脂E-51体系(含有1%质最分数的DMP-30)的非等温固化反应动力学进行了研究.通过机理函数(S)esták-Berggren方程很好地模拟了真实的固化反应过程.等转化率法求得反应活化能为69.78 kJ/mol.指前因子A的值为4.567×108min-1,n和m的值分别为1.082和0.456.根据得到的同化动力学方程计算可知,在固化温度为137.05℃时达到98%固化度的固化时间为115 min.

  2. CURING OF POLYMERIC COMPOSITES USING MICROWAVE RESIN TRANSFER MOULDING (RTM

    Directory of Open Access Journals (Sweden)

    R. YUSOFF

    2007-08-01

    Full Text Available The main objective of this work is to compare the difference between microwave heating and conventional thermal heating in fabricating carbon/epoxy composites. Two types of epoxy resin systems were used as matrices, LY5052-HY5052 and DGEBA-HY917-DY073. All composite samples were fabricated using resin transfer moulding (RTM technique. The curing of the LY5052-HY5052-carbon and the DGEBA-HY917-DY073-carbon composite systems, were carried out at 100 °C and 120 °C, respectively. Microwave heating showed better temperature control than conventional heating, however, the heating rate of the microwave cured samples were slower than the conventionally cured samples. This was attributed to the lower power (250 W used when heating with microwaves compared to 2000 W used in conventional heating. Study of thermal characteristics as curing progressed showed that the polymerisation reaction occurred at a faster rate during microwave curing than in conventional curing for both the DGEBA and the LY/HY5052 carbon composite systems. The actual cure cycle was reduced from 60 minutes to 40 minutes when using microwaves for curing DGEBA-carbon composites. As for LY/HY5052-carbon composites, the actual cure cycle was reduced from 3 hours to 40 minutes. Both conventional and microwave heating yielded similar glass transition temperatures (120 °C for DGEBA systems and 130 °C for LY/HY5052 systems. Microwave cured composites had higher void contents than conventionally cured composites (2.2-2.8% and 1.8-2.4% for DGEBA and LY/HY5052 microwave cured composites, respectively, compared to 0.2-0.4% for both DGEBA and LY/HY5052 thermally cured composites. C-scan traces showed that all composites, regardless of methods of curing, had minimal defects.

  3. Modification of (DGEBA epoxy resin with maleated depolymerised natural rubber

    Directory of Open Access Journals (Sweden)

    2008-04-01

    Full Text Available In this work, diglycidyl ether of bisphenol A (DEGBA type epoxy resin has been modified with maleated depolymerised natural rubber (MDPR. MDPR was prepared by grafting maleic anhydride onto depolymerised natural rubber. MDPR has been characterized by Fourier transform infrared (FT-IR spectroscopy and nuclear magnetic resonance spectroscopy. MDPR was blended with epoxy resin at three different ratios (97/3, 98/2 and 99/1, by keeping the epoxy resin component as the major phase and maleated depolymerised natural rubber component as the minor phase. The reaction between the two blend components took place between the acid/anhydride group in the MDPR and the epoxide group of the epoxy resin. The proposed reaction schemes were supported by the FT-IR spectrum of the uncured Epoxy/MDPR blends. The neat epoxy resin and Epoxy/MDPR blends were cured by methylene dianiline (DDM at 100°C for three hours. Thermal, morphological and mechanical properties of the neat epoxy and the blends were investigated. Free volume studies of the cured, neat epoxy and Epoxy/MDPR blends were correlated with the morphological and mechanical properties of the same systems using Positron Annihilation Lifetime Studies.

  4. Cure Monitoring and Control with Combined Dielectric/Temperature Probes.

    Science.gov (United States)

    1983-01-10

    DGEBA with expressions include an additional menthane diamine at 90*C were used parameter, 8, which accounts for to make the plots (the actual data...parameters to match Fig. 2 data. DGEBA cured with menthane diamine at Frequencies are 1,10,100 and 1000 Rz 900C. -5- ally with time (following the to slow down...mum. An example of such a result ure 2 shows plots correspondizg to is presented in Section 3.1 below. the model curves of Fig. 1 for DGEBA cured

  5. Octasilsesquioxane-reinforced DGEBA and TGDDM epoxy nanocomposites: Characterization of thermal, dielectric and morphological properties

    Energy Technology Data Exchange (ETDEWEB)

    Nagendiran, Shanmugam [Department of Chemical Engineering, Anna University, Chennai 600 025 (India); Alagar, Muthukaruppan, E-mail: mkalagar@yahoo.com [Department of Chemical Engineering, Anna University, Chennai 600 025 (India); Hamerton, Ian [Chemical Sciences Division, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)

    2010-05-15

    Epoxy resin nanocomposites, based on the diglycidyl ether of bisphenol-A (DGEBA) and tetraglycidyl diamino diphenyl methane (TGDDM), are prepared via in situ co-polymerization with 4,4'-diaminodiphenylsulfone (DDS) in the presence of octa-aminophenyl silsesquioxane (OAPS) at levels of up to 20 wt.% of the latter. The curing reaction involving epoxy, DDS and OAPS is investigated using Fourier transform infrared (FTIR) spectroscopy. Differential scanning calorimetry and dynamic mechanical analysis show that the glass transition temperatures of the polyhedral oligomeric silsesquioxane (POSS) containing nanocomposites are higher than the corresponding neat epoxy systems at lower concentrations of POSS ({<=}3 wt.%). Thermogravimetric analysis indicates that the POSS-epoxy nanocomposites display high ceramic yields, suggesting improved flame retardancy. The increasing concentration of OAPS into epoxy-amine networks exhibits a decreasing trend in the values of dielectric constant compared with those values obtained from neat epoxy systems. The higher epoxy functionality present in TGDDM leads to nanocomposites which possess enhanced thermal stability and higher dielectric constants than the DGEBA-based nanocomposites. X-ray diffraction analysis reveals that the molecular level reinforcement of POSS cages occurs in both the cases of DGEBA- and TGDDM-based hybrid epoxy nanocomposites. Furthermore, homogeneous dispersion of POSS cages in the epoxy matrices is evidenced by scanning electron microscopy, which further confirms that the POSS molecule has become an integral part of the organic-inorganic inter-cross-linked network systems.

  6. AFM and XRD characterization of silver nanoparticles films deposited on the surface of DGEBA epoxy resin by ion sputtering

    Directory of Open Access Journals (Sweden)

    José Elisandro de Andrade

    2013-01-01

    Full Text Available In this work, silver atoms were deposited by ion sputtering on the surface of diglycidyl ether of bisphenol A (DGEBA epoxy resin cured at 150 °C for 6 hours in air. The films of DGEBA and its precursors were characterized by Raman spectroscopy to identify the main functional groups and their relationship with the deposited silver atoms. Silver thin films of 5, 10, 15 and 20 nm were deposited on the epoxy resin at room temperature. Both the initial film of DGEBA and the subsequent silver thin film were analyzed by Atomic Force Microscopy (AFM in the non-contact mode. Silver thin films were also analyzed using X-ray diffraction (XRD at room temperature. The AFM results showed the formation of silver crystallites on the surface of DGEBA at very low coverage whereas XRD indicated that most of them had their main axis aligned to the normal of the surface. An increase in the coverage led to an increase in the grain size as indicated by AFM. However, XRD results indicated that the crystallite size remained almost constant while the appearance of peaks corresponding to other crystalline orientations suggests the coalescence of the original crystallites and an increase in size of the more dense planes, namely [111].

  7. AFM and XRD characterization of silver nanoparticles films deposited on the surface of DGEBA epoxy resin by ion sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Jose Elisandro de; Machado, Rogerio; Macedo, Marcelo Andrade [Universidade Federal de Sergipe (UFSE), Aracaju, SE (Brazil). Programa de Pos-graduacao em Fisica; Cunha, Frederico Guilherme Carvalho [Universidade Federal de Sergipe (UFSE), Aracaju, SE (Brazil). Programa de Pos-graduacao em Ciencia e Engenharia de Materiais

    2012-07-01

    In this work, silver atoms were deposited by ion sputtering on the surface of diglycidyl ether of bisphenol A (DGEBA) epoxy resin cured at 150 Degree-Sign C for 6 hours in air. The films of DGEBA and its precursors were characterized by Raman spectroscopy to identify the main functional groups and their relationship with the deposited silver atoms. Silver thin films of 5, 10, 15 and 20 nm were deposited on the epoxy resin at room temperature. Both the initial film of DGEBA and the subsequent silver thin film were analyzed by Atomic Force Microscopy (AFM) in the non-contact mode. Silver thin films were also analyzed using X-ray diffraction (XRD) at room temperature. The AFM results showed the formation of silver crystallites on the surface of DGEBA at very low coverage whereas XRD indicated that most of them had their main axis aligned to the normal of the surface. An increase in the coverage led to an increase in the grain size as indicated by AFM. However, XRD results indicated that the crystallite size remained almost constant while the appearance of peaks corresponding to other crystalline orientations suggests the coalescence of the original crystallites and an increase in size of the more dense planes, namely [111]. (author)

  8. AFM and XRD characterization of silver nanoparticles films deposited on the surface of DGEBA epoxy resin by ion sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Jose Elisandro de; Machado, Rogerio; Macedo, Marcelo Andrade; Cunha, Frederico Guilherme Carvalho [Clinica de Medicina Nuclear e Radiologia de Maceio (MedRadiUS), Radiology and Imaging Diagnosis at Universidade Federal de Alagoas (UFAL), Maceio, AL (Brazil)

    2012-07-01

    In this work, silver atoms were deposited by ion sputtering on the surface of diglycidyl ether of bisphenol A (DGEBA) epoxy resin cured at 150 deg C for 6 hours in air. The films of DGEBA and its precursors were characterized by Raman spectroscopy to identify the main functional groups and their relationship with the deposited silver atoms. Silver thin films of 5, 10, 15 and 20 nm were deposited on the epoxy resin at room temperature. Both the initial film of DGEBA and the subsequent silver thin film were analyzed by Atomic Force Microscopy (AFM) in the non-contact mode. Silver thin films were also analyzed using X-ray diffraction (XRD) at room temperature. The AFM results showed the formation of silver crystallites on the surface of DGEBA at very low coverage whereas XRD indicated that most of them had their main axis aligned to the normal of the surface. An increase in the coverage led to an increase in the grain size as indicated by AFM. However, XRD results indicated that the crystallite size remained almost constant while the appearance of peaks corresponding to other crystalline orientations suggests the coalescence of the original crystallites and an increase in size of the more dense planes, namely [111]. (author)

  9. Effect of Amine Catalyst Work on Epoxy / Anhydride Curing System%胺类促进剂对环氧树脂/酸酐固化体系的影响

    Institute of Scientific and Technical Information of China (English)

    刘琳; 张晓逆

    2012-01-01

    Adopting liquid methyltetrahydro phthalic anhydride as curing agent, multiplicate amine catalyst (including aliphatic ethanol amine, cycloaliphatic amine, aliphatic amine, quaternary ammonium salt, urea) were used to study diglycidyl ether bisphnol-A epoxy resin system. The best formula was confirmed from the aspects of amine catalyst compatibility, gel time, Tg, pot life etc. The results showed that cycloaliphatic amine (N,N-dimethylcyclohexylamine), aliphatic amine (N-dimethylpropane-l, 3-diamine), quaternary ammonium salt ( 2,2-dimethyl-Propanoic acid ammonium salt) could accelerate the curing system by decreasing the curing temperature from 160? to 100-120? and satisfied the mechanical properties request of FRP wind and casting / encapsulation.%以液体四氢甲基苯酐为固化剂,选用了多种胺类促进剂(包括脂肪类乙醇胺、脂环胺、脂肪胺、季胺盐、脲类)对双酚A缩水甘油醚类环氧树脂固化体系进行研究.从固化促进剂的相容性、凝胶时间、玻璃化转化温度、可使用时间等方面确定最佳配方.研究表明,脂环胺(N,N-二甲环己胺)、脂肪胺[三(二甲胺基丙基)胺]、季胺盐(2,2-二甲基丙酸季胺盐)可以促进双酚A缩水甘油醚类环氧树脂/液体四氢甲基苯酐固化体系的固化,并能使该体系的固化温度从160℃降低到100~120℃,力学性能达到玻璃钢缠绕和灌封浇注料的要求.

  10. SYNTHESIS,CHARACTERIZATION OF DIAMIDE-DIIMIDE-DIAMINES BASED ON L-CYSTEINE AMINO ACID AND THEIR EFFECT ON THE THERMAL PROPERTIES OF DIGLYCIDYL ETHER OF BISPHENOL-A(DGEBA)

    Institute of Scientific and Technical Information of China (English)

    Darshana; Priti Malhotra; A.K.Narula

    2009-01-01

    The curing behavior of diglycidyl ether of bisphenol-A(DGEBA)with aromatic diamide-diimide-diamines having aryl ether,sulfone and methylene linkages was studied by differential scanning calorimetry(DSC).Nine diamide-diimide diamines of varying structure were synthesized by reacting 1 mole of dianhydride with 2 moles of L-cysteine(S)in a mixture of acetic acid and pyridine(3:2 V/V)followed by activation with thionyl chloride(SOCl2)and then condensation with excess of diamines.Structural characterization of diamide-diimide-diamines was done by using FTIR,1H-NMR,13C-NMR spectroscopy and elemental analysis.The peak exotherm temperature(Tp)was lowest in DGEBA cured using EPSM and highest in DGEBA cured using ENSS.Thermal stability of the isothermally cured DGEBA with diamide-diimide-diamines was investigated using dynamic thermogravimetry(TGA)in nitrogen atmosphere,and it was found that NTDA based diamide-diimide-diamines provided good stability to DGEBA.The char yield was highest for resin cured with ENSE which might be due to the presence of more compact structure i.e.naphthalene.

  11. Edge-Selectively Functionalized Graphene-Like Platelets as a Co-curing Agent and a Nanoscale Additive to Epoxy Resin

    Science.gov (United States)

    2012-08-12

    epoxy resin used as the matrix material was diglycidyl ether of bisphenol A ( DGEBA ), supplied by the Kukdo Chemical Co. The curing agent 4,4...curing agent and as a nanoscale additive to epoxy resin. Resin mixtures with different loadings of AB-graphite and MDA (27 wt% to DGEBA ) were cast on a

  12. Chemical Interpretation of the Relaxed Permittivity during Epoxy Resin Cure.

    Science.gov (United States)

    1984-11-30

    contributions of other polar groups and their time variation are included. The isothermal cure of a stoichiometric mixture of a DGEBA epoxy resin, EPON 825. with...the DGEBA molecule, and since it contains only a single epoxide. this material does not crosslink. At low temperatures and at all frequencies, the...ratios of DGEBA and DDS gave an epoxy dipole moment of 8.SE-30 C-u and an amine dipole moment of 19.8E-30 C-m [10]. The experimental data and the curves

  13. Critical behavior of anhydride cured epoxies

    Science.gov (United States)

    Trappe, V.; Richtering, W.; Burchard, W.

    1992-07-01

    Critical behavior was studied with a crosslinking system obtained by living anionic polymerization, where the primary chain length was kept constant and the crosslinking density was varied. Gelation was found at a critical ratio of crosslinker per chain X_c=0.884± 0.004. Different samples from the pre gel region were studied by dynamic and static light scattering in dilute solution and oscillatory rheology in melt. The exponents γ = 1.75± 0.38 and ν = 0.98± 0.19, determined from M_w and R_g dependence on (X_c-X), are in accordance with three dimensional percolation theory. The distribution of diffusion coefficients obtained by inverse Laplace transformation of the time correlation function shows power law behavior in a limited interval, from which an exponent tau = 2.17± 0.03 is derived. Rheological measurements show a systematic change of G^{prime}(ω) and G''(ω) from typical liquid to the critical gel behavior, where tan δ = G''(ω)/G^{prime}(ω) becomes frequency independent.

  14. Physicochemical and mechanical interfacial properties of trifluorometryl groups containing epoxy resin cured with amine

    Energy Technology Data Exchange (ETDEWEB)

    Park, Soo-Jin [Advanced Materials Division, Korea Research Institute of Chemical Technology, PO Box 107, Yusong, Daejeon 305-600 (Korea, Republic of)]. E-mail: psjin@krict.re.kr; Jin, Fan-Long [Advanced Materials Division, Korea Research Institute of Chemical Technology, PO Box 107, Yusong, Daejeon 305-600 (Korea, Republic of); Shin, Jae-Sup [Department of Chemistry, Chungbuk National University, Chongju 361-763 (Korea, Republic of)

    2005-01-15

    A phenyl-trifluoromethyl (-Ph-CF{sub 3}) groups modified epoxy resin, diglycidylether of bisphenol A-fluorine (DGEBA-F), was synthesized and the physical properties, such as curing behaviors, thermal stabilities, and dielectric constant of the DGEBA-F/4,4'-diaminodiphenyl methane (DDM) system were investigated and compared with commercial DGEBA/DDM system. For the mechanical behaviors of the specimens, the fracture toughness and impact tests were performed, and their fractured surfaces were examined by using a scanning electron microscope (SEM). The dielectric constant values of the DGEBA-F/DDM system were lower than those of the DGEBA/DDM system and the mechanical properties of the casting DGEBA-F specimens were higher than those of the DGEBA specimens. This was probably due to the fact that the introduction of the -Ph-CF{sub 3} groups into the side chain of the epoxy resin resulted in improving the electrical properties and toughness of the cured DGEBA-F epoxy resin.

  15. SYNTHESIS OF 2,4,6-TRI(HYDROXYLPHENYLMETHYLAMINO)-s-TRIAZINE AND ITS CURING BEHAVIOR AND MECHANISM WITH DGEBA%2,4,6-三(羟基苯甲基氨基)-均三嗪的合成及其与双酚A型环氧树脂的固化行为研究

    Institute of Scientific and Technical Information of China (English)

    闵玉勤; 张兴宏; 赵晖; 戚国荣

    2006-01-01

    合成了一种含三嗪环结构的环氧树脂固化剂2,4,6-三(羟基苯甲基氨基)-均三嗪(MFP).用动态DSC和原位红外光谱对MFP/DGEBA(双酚A型环氧树脂)体系的固化行为进行了研究.动态DSC研究表明,由于MFP分子结构中存在两种活泼氢(酚羟基氢和仲胺氢),固化反应存在明显的两个峰,相对应的表观活化能分别为70.5 kJ·mol-1和86.5 kJ·mol-1(Kissinger法),通过与另一相似化合物固化DGEBA的比较可知,在MFP固化DGEBA的过程中,酚羟基与环氧基反应相对较难.原位红外动力学结果很好地支持了上述结论.

  16. Study on Phthalic Anhydride Cured Diglycidyl Ether of Bisphenol A Decomposed by Tetramethyl Ammonium Hydroxide%四甲基氢氧化铵降解苯酐固化双酚A型环氧树脂的研究

    Institute of Scientific and Technical Information of China (English)

    姜坤; 罗炎

    2013-01-01

    将四甲基氢氧化铵(TMAH)降解聚酯的方法移植用于降解苯酐(PA)固化双酚A型环氧树脂(DGEBA),降解生成的邻苯二甲酸二甲酯(DMP)可被气相色谱-质谱(GC-MS)快速检测到,同时通过内标法考察了TMAH用量对降解率的影响,结果表明TMAH降解苯酐固化环氧树脂效率较高,甲酯化率在95%以上.此项研究为剖析毫克级酸酐固化环氧树脂中的固化剂提供了一种快速且有效的方法.

  17. Comparative investigation of thermal and mechanical properties of cross-linked epoxy polymers with different curing agents by molecular dynamics simulation.

    Science.gov (United States)

    Jeyranpour, F; Alahyarizadeh, Gh; Arab, B

    2015-11-01

    Molecular dynamics (MD) simulations were carried out to predict the thermal and mechanical properties of the cross-linked epoxy system composed of DGEBA resin and the curing agent TETA. To investigate the effects of curing agents, a comprehensive and comparative study was also performed on the thermal and mechanical properties of DGEBA/TETA and DGEBA/DETDA epoxy systems such as density, glass transition temperature (Tg), coefficient of thermal expansion (CTE) and elastic properties of different cross-linking densities and different temperatures. The results indicated that the glass transition temperature of DGEBA/TETA system calculated through density-temperature data, ∼ 385-395 °K, for the epoxy system with the cross-linking density of 62.5% has a better agreement with the experimental value (Tg, ∼ 400 °K) in comparison to the value calculated through the variation of cell volume in terms of temperature, 430-440 °K. They also indicated that CTE related parameters and elastic properties including Young, Bulk, and shear's moduli, and Poisson's ratio have a relative agreement with the experimental results. Comparison between the thermal and mechanical properties of epoxy systems of DGEBA/TETA and DGEBA/DETDA showed that the DGEBA/DETDA has a higher Tg in all cross linking densities than that of DGEBA/TETA, while higher mechanical properties was observed in the case of DGEBA/TETA in almost all cross linking densities.

  18. α-Costic anhydride

    Directory of Open Access Journals (Sweden)

    Moha Berraho

    2010-03-01

    Full Text Available The title compound [systematic name: 2-(4a,8-dimethyl-1,2,3,4,4a,5,6,8a-octahydronaphthalen-2-ylacrylic acid anhydride], C30H42O3, is a new isocostic anhydride which was synthesized from the aerial part of Inula Viscosa (L Aiton [or Dittrichia Viscosa (L Greuter]. The molecule adopts an essentially linear shape with two terminal fused-rings bridged by the anhydride group. The external rings have the same conformation (half-chair while each of the two inner rings has an almost ideal chair conformation. In the crystal, intermolecular C—H...O interactions link the molecules into a two-dimensional array in the bc plane.

  19. α-Costic anhydride.

    Science.gov (United States)

    Tebbaa, Mohamed; Akssira, Mohamed; Elhakmaoui, Ahmed; El Ammari, Lahcen; Benharref, Ahmed; Berraho, Moha

    2010-02-13

    THE TITLE COMPOUND [SYSTEMATIC NAME: 2-(4a,8-dimethyl-1,2,3,4,4a,5,6,8a-octa-hydro-naphthalen-2-yl)acrylic acid anhydride], C(30)H(42)O(3), is a new isocostic anhydride which was synthesized from the aerial part of Inula Viscosa- (L) Aiton [or Dittrichia Viscosa- (L) Greuter]. The mol-ecule adopts an essentially linear shape with two terminal fused-rings bridged by the anhydride group. The external rings have the same conformation (half-chair) while each of the two inner rings has an almost ideal chair conformation. In the crystal, inter-molecular C-H⋯O inter-actions link the mol-ecules into a two-dimensional array in the bc plane.

  20. Curing Study of Epoxy/clay Nanocomposite by a New Aromatic Diamine Functional Curing Agent

    Directory of Open Access Journals (Sweden)

    Seyed Mahdi Saadati

    2013-12-01

    Full Text Available The curing behavior of an epoxy/clay nanocomposite system composed of diglycidyl ether of bisphenol A (DGEBA epoxy resin with a new aromatic diamine curing agent and organically modified clay was investigated. Epoxy/clay nanocomposite samples were prepared by mixing DGEBA, different percentages of nanoclay (1, 3, 5, 7, and 9% and 4-(4-(2,6-diphenylpyridin-4-ylphenoxybenzene-1,3-diamine (DAP. The optimum ratio of the epoxy/clay nanocomposite system (3% was investigated by total enthalpy of the curing reaction from differential scanning calorimetry (DSC thermograms. The kinetic parameters such as activation energy, pre-exponential factor, and rate constant were obtained from DSC data.

  1. Effect of gamma irradiation on mechanical and thermal properties of DGEBA/cycloaliphatic amine networks with potential for medical applications; Efeito da irradiacao gama nas propriedades mecanicas e termicas de redes DGEBA/amina cicloalifatica com potencial para aplicacoes medicas

    Energy Technology Data Exchange (ETDEWEB)

    Neves, Juliana C.; Silva, Glaura G., E-mail: glaura@qui.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Mendes, Marcio W. Duarte; Bressiani, Ana H.; Bressiani, Jose C. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Garcia, Filiberto Gonzalez [Universidade Federal de Itajuba (UNIFEI), MG (Brazil)

    2013-07-01

    Two epoxy polymers based on diglycidyl ether of bisphenol A (DGEBA), cured with piperidine (Pip) and 4,4'-diamino-3,3'-dimethyldicyclohexylmethane (3DCM), were characterized before and after treatment with γ irradiation. The changes in the mechanical and thermal properties were studied by elastic modulus, glass transition temperature and degradation temperature measurements. A dose of 50 kGy of irradiation caused subtle variations in properties such as rigidity and stability, which are relevant from the fundamental point of view. The variations do not imply on negative impact when considering the stage of sterilization during the use of these systems as a biomaterial in the medical area. (author)

  2. Influence of nanofillers on the thermal and mechanical behavior of DGEBA-based adhesives for bonded-in timber connections

    Science.gov (United States)

    Ahmad, Z.; Ansell, M. P.; Smedley, D.

    2006-09-01

    Results of an experimental investigation into the thermal behavior and mechanical properties of a room-temperature-cured epoxy adhesive (diglycidyl ether of bisphenol A, DGEBA) cross-linked with polyetheramines and filled with different fillers, namely nanosilica, liquid rubber (CTBN), and clay, are reported. The nanosilica and liquid rubber increased the flexural strength and elastic modulus of the adhesive systems; the addition of clay particles raised the elastic modulus significantly, but embrittled the adhesive. Establishing a correct cure time is very important for bonded-in timber structures, as it will affect the bond strength. A study on the effect of cure time on the flexural strength was carried out, from which it follows that the adhesives should be cured for at least 20 days at room temperature. The damping characteristics and the glass-transition temperature of the adhesives were determined by using a dynamic mechanical thermal analysis. The results showed that the filled adhesives had a higher storage modulus, which was in agreement with the elastic moduli determined from static bending tests. The introduction of the fillers increased its glass-transition temperature considerably.

  3. Comparative study of the use of non-ionizing and ionizing radiation in the cure of epoxy resin: microwave versus electron electron

    Energy Technology Data Exchange (ETDEWEB)

    Kersting, Daniel, E-mail: daniel.kersting@usp.br [Centro Tecnologico da Marinha em Sao Paulo (CTMSP/USP), Sao Paulo, SP (Brazil); Wiebeck, Helio, E-mail: hwiebeck@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Escola Politecnica. Dept. de Engenharia Metalurgica; Marinucci, Gerson; Silva, Leonardo G.A. e, E-mail: marinuci@ipen.br, E-mail: gasilva@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    Several processes for curing epoxy resins were developed over the years. Two methods are discussed in this paper, in order to present the main advantages and disadvantages of using microwave radiation (non-ionizing radiation) and electron beam radiation (ionizing radiation). The microwave radiation is a non-ionizing radiation, with great power of penetration and transfer of heat in microwave absorbing materials, or materials with microwave absorbing fillers. The frequency usually used in research and development is 2.45 GHz, the same available in commercial equipment. The microwave effect provides increase on the collision velocity between the reactant which, combined with energy absorbed by the reaction system, accelerates the curing reaction. None modifications in the epoxy system are required to use microwave heating for the curing process.On the other hand, the electron beam is a form of ionizing radiation in which the high energy electrons have the ability to interact with the irradiated material and produce ions, free radicals, and molecules in excited state, which can be used to initiate and propagate a polymerization. Specific initiators are necessary for an effective cure of the resin. In this study, a DGEBA epoxy resin with initiators based on anhydride and amine was used under the same conditions indicated by the manufacturer. The curing of the catalyzed system was performed in a domestic microwave oven adapted for laboratory use. The degradation and glass transition temperatures were evaluated by thermal analysis techniques. For comparative purposes, it was used data available in the literature for electron beam irradiation. (author)

  4. 1-Butyl-3-methylimidazolium Salts as New Catalysts to Produce Epoxy-anhydride Polymers with Improved Properties

    OpenAIRE

    Mikhail S. Fedoseev; Gruzdev, Matvey S.; Lubov F. Derzhavinskaya

    2014-01-01

    We report the curing process of epoxy oligomers by using isomethyltetrahydrophthalic anhydride catalyzed with 1-butyl-3-methylimidazolium salts. Catalytic action has been ascertained to be dependent on the nature of anion. Salts with (Br-) and (PO4-) anions appeared to be most active. Formation of salt adducts with epoxy resin and anhydride is shown. Polymers having higher values of strength and glass transition temperature—as compared with similar epoxy systems cured in the presence of terti...

  5. The stability of new transparent polymeric materials: The epoxy trimethoxyboroxine system. Part 1: The preparation, characterization and curing of epoxy resins and their copolymers

    Science.gov (United States)

    Pearce, E.; Lin, S. C.

    1981-01-01

    The effects of resin composition, curing conditions fillers, and flame retardant additives on the flammability of diglycidyl ether of bisphenol-A (DGEBA) as measured by the oxygen index is examined. The oxygen index of DGEBA cured with various curing agents was between 0.198 to 0.238. Fillers and flame retardant additives can increase the oxygen index dependent on the material and the amount used. Changes in the basic cured resin properties can be anticipated with the addition of noncompatible additives. High flame resistant epoxy resins with good stability and mechanical properties are investigated.

  6. Cure Behaviors of epoxy resin initiated by methylanilinium slats as latent cationic curing agent.

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.J.; Kim, T.J.; Lee, C.J.; Lee, J.R. [Korea Research Institute of Chemical Technology, Taejeon (Korea); Park, J.K.; Shin, J.H. [Seoul National University, Seoul (Korea)

    2001-03-01

    The effect of novel N-crotyl-N, N-dimethyl-4-methylanilinium hexafluoroantimonate (CMH) curing agent as a thermal latent initiator on thermal behaviors, rheological properties, and thermal stability of diglycidylether of bisphenol A (DGEBA) epoxy cationic system was investigated. From DSC measurements of DGEBA/CMH system, it was shown that this system exhibits an excellent thermal latent characteristic at a given temperature. The conversion and conversion rate of DGEBA/CMH system increased with increasing the concentration of initiator, due to high activity of CMH. Rheological properties of the system were investigated under isothermal condition using a rheometer. The gelation time was obtained from the analysis of storage modulus (G'), loss modulus (G''), and damping factor (tan {delta}). As a result, the reduction of gelation time was affected by high curing temperature and concentration of CMH, resulting in high degree of network formation in cationic polymerization, due to difference of activity. The thermal stability of the cured epoxy resin was discussed in terms of the activation energy for decomposition and thermal factors determined from TGA measurements. (author). 29 refs., 3 tabs., 10 figs.

  7. Study of 3,3' vs. 4,4' DDS isomer curatives on physical properties and phenyl ring motions of DGEBA epoxy via molecular dynamics, deuterium NMR, and dielectric spectroscopy

    Science.gov (United States)

    Tucker, Samuel James

    The purpose of this research is to develop a multiscale understanding of crosslinked amorphous matrices, connecting molecular level events to macroscopic properties. To accomplish this goal, our methodology was to identify network architectures that influence molecular level energy dissipation through mechanisms such as bond rotations, torsions, and ring flips and then relate those molecular motions to macroscopic properties. Studies were accomplished on two aerospace grade matrices: the epoxy, diglycidyl ether of bisphenol A (DGEBA) cured with two amines, 3,3'-diaminodiphenyl sulfone (33DDS) and 4,4'-diaminodiphenyl sulfone (44DDS). The 33DDS/DGEBA and 44DDS/DGEBA served both to provide a baseline for experimental testing of aerospace matrices and to enable the comparison of a meta-substituted vs. para-substituted diamine in chemically isotropic systems. The results presented in the first seven chapters of the dissertation focus on these two matrices. Molecular Dynamics (MD) simulations provide a tool to quickly create networks with alterations in network architectures, such as crosslink density, aromaticity, sulfone content, pendant bulky groups, etc. MD can then be used to predict thermomechanical properties of these matrices and determine the effect of network architecture on properties. In this work, molecular dynamics simulations were used to accurately predict thermomechanical properties of 33DDS/DGEBA and 44DDS/DGEBA. Additionally, modifications to these baseline matrices were made in order to study the effect of network architecture and chemical composition of matrices. To bridge the gap in understanding between network architecture and ultimate matrix performance, molecular motions resulting from the network architecture and responsible for ultimate properties, must be understood. To analyze these molecular motions, various solid state Nuclear Magnetic Resonance (NMR) spectroscopic techniques, Dielectric Spectroscopy (DES), and Dynamic Mechanical Analysis

  8. Studies on the physico-mechanical and thermal characteristics of blends of DGEBA epoxy, 3,4 epoxy cyclohexylmethyl, 3',4'-epoxycylohexane carboxylate and carboxyl terminated butadiene co-acrylonitrile (CTBN)

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, Garima [Department of Plastic Technology, H. B. Technological Institute, Kanpur 208002 (India); Srivastava, Deepak [Department of Plastic Technology, H. B. Technological Institute, Kanpur 208002 (India)], E-mail: deepak_sri92@rediffmail.com

    2008-11-25

    Toughening of blend of diglycidyl ether of bisphenol-A (DGEBA) and 3,4 epoxy cyclohexylmethyl, 3',4'-epoxycylohexane carboxylate, i.e. cycloaliphatic epoxy resin (CAE) with varying weight ratios (0-25 wt%) of carboxyl terminated butadiene acrylonitrile (CTBN) copolymer have been investigated. Fourier transform infrared (FTIR) spectroscopic analysis established that the interaction between oxirane groups of DGEBA, CAE and CTBN were responsible for characteristics peak shifts in the blends compared to their counterparts. Physico-mechanical properties of the prepared samples, e.g. tensile, flexural and impact strengths showed an optimum concentration of CTBN (15 wt%) into epoxy matrix, which offered maximum toughening. Thermal stability of the prepared samples was analyzed by dynamic thermogravimetric runs. Cross-sections of the cured samples which failed during impact testing have been critically studied through scanning electron microscopic (SEM) analysis to gain insight into the phase morphology.

  9. Gelling and curing behaviors of benzoxazine/epoxy formulations containing 4,4 Prime -thiodiphenol accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Chow, W.S., E-mail: chowwenshyang@yahoo.com [Institut fuer Verbundwerkstoffe GmbH (Institute for Composite Materials), Kaiserslautern University of Technology, D-67663 Kaiserslautern (Germany); School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, Nibong Tebal 14300, Penang (Malaysia); Grishchuk, S.; Burkhart, T. [Institut fuer Verbundwerkstoffe GmbH (Institute for Composite Materials), Kaiserslautern University of Technology, D-67663 Kaiserslautern (Germany); Karger-Kocsis, J. [Polymer Technology, Faculty of Engineering and the Built Environment, Tshwane University of Technology, Pretoria 0001 (South Africa); Department of Polymer Engineering, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, H-1111 Budapest (Hungary)

    2012-09-10

    Highlights: Black-Right-Pointing-Pointer Gelling and curing behaviors of benzoxazine/epoxy with accelerator were studied. Black-Right-Pointing-Pointer The activation energy of gelling was assessed by Arrhenius equation. Black-Right-Pointing-Pointer The activation energy of curing was determined from dynamic DSC scans. Black-Right-Pointing-Pointer 4,4 Prime -Thiodiphenol can act as co-reactive accelerator for benzoxazine/epoxy blends. Black-Right-Pointing-Pointer 4,4 Prime -Thiodiphenol markedly reduced the gel time and the activation energy. - Abstract: Benzoxazine (BOX)/diglycidyl ether of bisphenol A (DGEBA) based epoxy resins (BOX/DGEBA = 100/0, 75/25 and 50/50 wt.%) with and without 4,4 Prime -thiodiphenol accelerator (DT300) were prepared. The gelling and curing behaviors of the BOX and BOX/DGEBA mixtures in presence and absence of DT300 (10 parts per hundred resin, phr) were investigated using plate-plate rheometry and differential scanning calorimetry (DSC). The gel time was determined in isothermal scans at three different temperatures (T = 180, 200, and 220 Degree-Sign C). Dynamic DSC scans were registered at four heating rates ({beta} = 5, 10, 15, and 20 Degree-Sign C min{sup -1}, respectively). The activation energy of gelling was assessed by an Arrhenius, whereas that of the curing by the Kissinger and Ozawa methods. Combination of BOX with DGEBA delayed the gel formation and increased the activation energy of both gelling and curing processes compared to neat BOX resin. By contrast, addition of 4,4 Prime -thiodiphenol as co-reactive accelerator markedly reduced the gel time and the activation energy of both gelling and curing of BOX and BOX/DGEBA formulations.

  10. SYNTHESIS OF A HYPERBRANCHED POLYETHER EPOXY THROUGH ONESTEP PROTON TRANSFER POLYMERIZATION AND ITS APPLICATION AS A TOUGHENER FOR EPOXY RESIN DGEBA

    Institute of Scientific and Technical Information of China (English)

    Jian-yong Lv; Yan Meng; Li-fan He; Xiao-yu Li; Hai-qiao Wang

    2012-01-01

    A novel liquid hyperbranched polyether epoxy (HBPEE) based on commercially available hydroquinone (HQ) and 1,1,1-trihydroxymethylpropane triglycidyl ether (TMPGE) was synthesized through an A2 + B3 one-step proton transfer polymerization.In order to improve the toughness,the synthesized HBPEE was mixed with diglycidyl ether of bisphenol A (DGEBA) in different ratios to form hybrids and cured with triethylenetetrarnine (TETA).Thermal and mechanical properties of the cured hybrids were evaluated.Results show that addition of HBPEE can improve the toughness of cured hybrids remarkably at < 20 wt% loading,without compromising the tensile strength.However,the glass transition temperature (Tg) of the cured hybrids decreases with increasing HBPEE content.Fracture surface images from scanning electron microscope show oriented fibrils in hybrids containing HBPEE.The formation and orientation of the fibrils can absorb energy under impact and lead to an improvement of toughness.Furthermore,based on the morphology of fractured surfaces and the single Tg in each hybrid,no sign of phase separation was found in the cured hybrid systems.As a result,the toughening mechanism could be explained by in situ homogeneous toughening mechanism rather than phase separation mechanism.

  11. EFFECT OF NANOSILICA ON THE KINETICS OF CURE REACTION AND THERMAL DEGRADATION OF EPOXY RESIN

    Institute of Scientific and Technical Information of China (English)

    M. Ghaemy; M. Bazzar; H. Mighani

    2011-01-01

    Nanocomposites from nanoscale silica particles (NS), diglycidylether of bisphenol-A based epoxy (DGEBA), and 3,5-diamino-N-(4-(quinolin-8-yloxy) phenyl) benzamide (DQPB) as curing agent were obtained from direct blending of these materials. The effect of nanosilica (NS) particles as catalyst on the cure reaction of DGEBA/DQPB system was studied by using non-isothermal DSC technique. The activation energy (Ea) was obtained by using Kissinger and Ozawa equations.The Ea value of curing of DGEBA/DQPB/10% NS system showed a decrease of about 10 KJ/mol indicating the catalytic effect of NS particles on the cure reaction. The Ea values of thermal degradation of the cured samples of both systems were 148 KJ/mol and 160 KJ/mol, respectively. The addition of 10% of NS to the curing mixture did not have much effect on the initial decomposition temperature (Ti) but increased the char residues from 20% to 28% at 650℃.

  12. Investigação da cinética de cura por calorimetria diferencial exploratória (DSC de resinas epóxi preparadas a partir de óleo de soja epoxidado com diferentes anidridos e aminas terciárias Investigation of the kinetics of cure by differential scanning calorimetry (DSC of epoxy resins prepared from epoxidized soybean oil with different anhydrides and tertiary amines

    Directory of Open Access Journals (Sweden)

    Ana P. O. Costa

    2011-01-01

    Full Text Available No presente trabalho, utilizou-se a calorimetria diferencial exploratória (DSC para investigar a cinética da reação de cura de resinas epóxi produzidas a partir da reação do óleo de soja epoxidado (ESO, com os anidridos dodecenilsuccínico (DDS, maleico (MAL, ftálico (FTA, succínico (SUC e hexahidroftálico (CH, atuando como agentes de cura, e na presença de aminas terciárias como a trietilamina (TEA, a N,N'-dimetilanilina (ARO e a 1,4- diazobiciclo [2,2,2] octano (DABCO, atuando como catalisadores. A taxa de aquecimento, a natureza química e a estrutura do anidrido e das aminas influenciaram a reação de cura. Os métodos dinâmicos de Kissinger, Ozawa e de Barrett foram utilizados para calcular a energia de ativação dos sistemas onde se variou o anidrido. Observou-se que os anidridos mais reativos foram o DDS e maleico que apresentaram os menores valores de energias de ativação. No estudo da influência do catalisador, utilizou-se o método de Barrett para determinar as energias de ativação das reações com as diferentes aminas. A amina cicloaliafática (DABCO foi a mais reativa obtendo-se o menor valor de energia de ativação (Ea = 51 kJ.mol-1 e fator pré-exponencial (ln A0 = 9 s-1.In the present work, differential scanning calorimetry (DSC was used to investigate the curing reaction kinetics of epoxy resins produced from reaction of epoxidized soybean oil (ESO with cyclic anhydrides dodecenylsuccinic (DDS, maleic (MAL, phthalic (PA, succinic (SUC and hexahydrophthalic (CH, in the presence of tertiary amines such as triethylamine (TEA, N,N-dimethylaniline (ARO and 1,4-diazabicyclo [2,2,2] octane (DABCO. The heating rate, the nature and structure of anhydrides and amines were found to affect the curing reaction. The dynamic methods of Kissinger, Ozawa and Barrett were used to calculate the activation energy of the reactions where different anhydrides were used. DDS and maleic anhydrides were more reactive than the others

  13. COMPARISON OF THE E44 EPOXY RESINS IN DIFFERENT CONTENTS OF CURING AGENT BY MICROWAVE AND THERMAL CURING METHODS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper discusses the fundamental principle of microwave heating, and based on the advantages of microwave heating, use maleic anhydride as curing agent.The technology of microwave curing E44 epoxy resins is investigated,the mechanical properties of cured epoxy resin samples in different contents of curing agent by microwave and thermal curing methods are measured respectively, and then some experimental results for which are obtained.At last, this paper analyses why microwave curing can improve mechanical property of epoxy resin.

  14. Preparation, curing kinetic and properties of a novel amine with flexible polyoxypropylene side chain curing agent for epoxy resin

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guiyou, E-mail: guiyouwang@ecust.edu.cn; Jiang, Guanlan; Zhang, Jie

    2014-08-10

    Highlights: • Novel amines with different length of flexible polyoxypropylene side chain (AFPE) were synthesized. • The non-isothermal curing kinetics of DGEBA/AFPEs were studied in detail. • Structure, morphology and physical properties of AFPEs modified diethylenetriamine/DGEBA systems were studied, and results showed that AFPE was a novel and effective toughening agent for epoxy resins. - Abstract: A novel amine with flexible polyoxypropylene side chain (AFPE) was synthesized and characterized with FT-IR and NMR. Then, AFPEs with different molecular weight were used as a curing agent for diglycidyl ether of bisphenol A (DGEBA), and non-isothermal reaction was detected with DSC. The kinetic parameters of the curing process were determined by Málek method. A two-parameter (m, n) autocatalytic model (Šesták–Berggren equation) was found to be adequate to describe the reaction-controlled kinetics of the studied epoxy resins, yet was insufficient in depicting the diffusion-controlled kinetics of the epoxy resins. The values of E{sub a} depended on the molecular weight of AFPEs, and increased with longer polyoxypropylene chain length in the AFPE. Dynamic mechanical analysis of AFPEs modified DGEBA/diethylenetriamine systems found that with the increasing molecular weight of AFPEs, α relaxation temperature, β relaxation temperature and crosslinking density decreased, while impact strength and elongation at break improved. From scanning electron microscope, tensile surfaces were rougher and sizes of cavities in the surface became larger with the increasing molecular weight of AFPEs. Our study showed that AFPE was a novel and effective toughening agent for epoxy resins.

  15. Curing kinetics and thermomechanical properties of latent epoxy/carbon fiber composites

    Science.gov (United States)

    Dalle Vacche, S.; Michaud, V.; Demierre, M.; Bourban, P.-E.; Månson, J.-A. E.

    2016-07-01

    In this work, resins based on diglycidyl ether of bisphenol A (DGEBA) epoxy and a latent hardener, dicyandiamide (DICY), as well as carbon fiber (CF) composites based on them, were prepared with three commercial accelerators: a methylene bis (phenyl dimethyl urea), a cycloaliphatic substituted urea, and a modified polyamine. The curing kinetics of the three DGEBA/DICY/accelerator systems were investigated by chemorheology and differential scanning calorimetry (DSC), in isothermal and over temperature change conditions. Differences in the reaction onset temperature, and in the glass transition temperature (Tg) were highlighted. For curing of thick resin samples, a slow curing cycle at the lowest possible temperature was used, followed by high temperature (160 - 180 °C) post-curing. Indeed, fast curing at higher temperatures caused the formation of hot spots and led to local burning of the samples. The obtained thermomechanical properties, assessed by ultimate tensile testing and dynamic mechanical analysis (DMA) in single cantilever configuration, were all in the expected range for epoxy resins, with tensile moduli close to 3 GPa and Tg > 140 °C. The longterm stability of these resins at room temperature was verified by DSC. Composite samples were prepared by hand lay-up by manually impregnating four layers of 5-harness satin CF textile, and curing in vacuum bag. Impregnation quality and void content were assessed by optical microscopy. The flexural properties of the post-cured composites were assessed by three-point bending test at room temperature and showed no relevant differences, all composites having bending moduli of 45 - 50 GPa. Finally, composites cured with a faster high temperature curing cycle (20 min at 140 °C) were prepared with the DGEBA/DICY/ methylene bis (phenyl dimethyl urea) system, obtaining similar properties as with the slower curing cycle, showing that the prepreg system allowed more flexibility in terms of curing cycle than the bulk resin

  16. Tannic Acid as a Bio-Based Modifier of Epoxy/Anhydride Thermosets

    OpenAIRE

    Xiaoma Fei; Fangqiao Zhao; Wei Wei; Jing Luo; Mingqing Chen; Xiaoya Liu

    2016-01-01

    Toughening an epoxy resin by bio-based modifiers without trade-offs in its modulus, mechanical strength, and other properties is still a big challenge. This paper presents an approach to modify epoxy resin with tannic acid (TA) as a bio-based feedstock. Carboxylic acid-modified tannic acid (TA–COOH) was first prepared through a simple esterification between TA and methylhexahydrophthalic anhydride, and then used as a modifier for the epoxy/anhydride curing system. Owing to the chemical modifi...

  17. 1-Butyl-3-methylimidazolium Salts as New Catalysts to Produce Epoxy-anhydride Polymers with Improved Properties

    Directory of Open Access Journals (Sweden)

    Mikhail S. Fedoseev

    2014-01-01

    Full Text Available We report the curing process of epoxy oligomers by using isomethyltetrahydrophthalic anhydride catalyzed with 1-butyl-3-methylimidazolium salts. Catalytic action has been ascertained to be dependent on the nature of anion. Salts with (Br- and (PO4- anions appeared to be most active. Formation of salt adducts with epoxy resin and anhydride is shown. Polymers having higher values of strength and glass transition temperature—as compared with similar epoxy systems cured in the presence of tertiary amines as catalysts—are prepared.

  18. High Tg and fast curing epoxy-based anisotropic conductive paste for electronic packaging

    Science.gov (United States)

    Keeratitham, Waralee; Somwangthanaroj, Anongnat

    2016-03-01

    Herein, our main objective is to prepare the fast curing epoxy system with high glass transition temperature (Tg) by incorporating the multifunctional epoxy resin into the mixture of diglycidyl ether of bisphenol A (DGEBA) as a major epoxy component and aromatic diamine as a hardener. Furthermore, the curing behavior as well as thermal and thermomechanical properties were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermomechanical analysis (TMA). It was found that Tg obtained from tan δ of DGEBA/aromatic diamine system increased from 100 °C to 205 °C with the presence of 30 percentage by weight of multifunctional epoxy resin. Additionally, the isothermal DSC results showed that the multifunctional epoxy resin can accelerate the curing reaction of DGEBA/aromatic diamine system. Namely, a high degree of curing (˜90%) was achieved after a few minutes of curing at low temperature of 130 °C, owing to a large number of epoxy ring of multifunctional epoxy resin towards the active hydrogen atoms of aromatic diamine.

  19. Relaxation Characteristics of 828 DGEBA Epoxy Over Long Time Periods

    Science.gov (United States)

    Hoo, Jasmine; Reprogle, Riley C.; Wisler, Brian; Arechederra, Gabriel K.; McCoy, John D.; Kropka, Jamie M.; Long, Kevin N.

    The mechanical relaxation response in uniaxial compression of a diglycidyl ether of bisphenol-A epoxy was studied over long time periods. The epoxy, 828DEA, was Epon 828 cured with diethanolamine (DEA). A sample was compressed at constant strain rate and held at various strain levels for days to allow the sample to relax. The sample was then compressed further and held once more. The relaxation curves were fit with a stretched exponential function. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  20. Ageing of the DGEBA/TETA epoxy system with off-stoichiometric compositions

    OpenAIRE

    d'Almeida José Roberto Moraes; Menezes Gustavo Wagner de; Monteiro Sérgio Neves

    2003-01-01

    An investigation was carried out on the room temperature ageing of off-stoichiometric DGEBA/TETA epoxy formulations. The results obtained show that the epoxy rich mixtures have their inherent brittleness increased by the ageing treatment due to recrystalization of the unreacted epoxy monomers, although homopolymerization could also play a minor role. The initial reaction steps dominated by the amine addition reactions control the macromolecular structure and the mechanical performance of the ...

  1. Processing of Clay/Epoxy Nanocomposites with a Three-Roll Mill Machine

    Science.gov (United States)

    2003-01-01

    diglycidyl ether of bisphenol A ( DGEBA ) epoxy resin cured with methyl tetrahydrophthalic anhydride hardener from Vantico was used as the matrix. 1...34) was used to disperse and exfoliate the nanoclay particles in the epoxy matrix. First, the epoxy resin ( DGEBA ) was placed between the feed and center

  2. Mechanical and Thermoviscoelastic Behavior of Clay/Epoxy Nanocomposites

    Science.gov (United States)

    2003-01-01

    bisphenol A ( DGEBA ) epoxy of subambient glass transition temperature (Tg) with 5% weight of montmorillonite. The authors showed that no big improvements...reinforced polymers for structural applications. The epoxy system considered here is an anhydride-cured epoxy consisting of a DGEBA epoxy resin cross-linked

  3. Materiali Polimerici Reticolati e Interpenetrati ottenuti per polimerizzazione sequenziale (Dual Curing) di oligomeri epossiacrilati modificati

    OpenAIRE

    Busatto, Eva

    2009-01-01

    The materials and methods used for the preparation of interpenetrated polymer network (IPN) by UV curing processes are reported. In particular, recent developments on the formation and characterization of some sequential IPN based on mixtures of commercially available diglycidyl ether of bisphenol-A (DGEBA) epoxy resins and UV curable epoxy-dimethacrylate resins are discussed. Finally, the photopolymerization kinetic behavior and thermal properties of some UV curable mixture...

  4. Effect of electron irradiation on the mechanical properties of DGEBA/DDM epoxy resins

    Energy Technology Data Exchange (ETDEWEB)

    Vignoud, Lionel E-mail: lionel.vignoud@insa-lyon.fr; David, Laurent; Sixou, Bruno; Vigier, Gerard; Stevenson, Isabelle

    2001-12-01

    The thermomechanical properties of diglycidyl ether of bisphenol A (DGEBA)/4-4 diaminodiphenylmethane (DDM) resins are analysed as a function of the irradiation dose. Irradiation results in a decrease of the glass transition temperature and of the elastic modulus in the rubbery region, ascribed to a destruction of crosslinks. The Arrhenius diagrams show that the {alpha} relaxation becomes faster, that the {beta} process is enhanced but that {gamma} relaxation is less modified by the irradiation. The effects of irradiation on the stress-strain curves suggest a spatial heterogeneity of the crosslink density.

  5. Microwave curing of initially compatible epoxy–poly(ethylene terephthalate) blends: DSC kinetic study and nano-structure analysis{sup ☆}

    Energy Technology Data Exchange (ETDEWEB)

    Zvetkov, V.L., E-mail: zvetval@yahoo.com; Simeonova-Ivanova, E.; Djoumaliisky, S.

    2014-11-10

    Graphical abstract: The curves proposed to tabulate the curing regime in microwave field. - Highlights: • The monitoring of the curing process in microwave field is the aim of the study. • We consider an approach to estimate the curing regime in microwave field. • We present physical evidences for obtaining nano-modified epoxy composites. - Abstract: Poly(ethylene terephthalate), PET, dissolved in diglycidyl ether of bisphenol-A epoxy resins, DGEBA, is used as a toughening modifier. Two DGEBA resins in the presence of PET have been cured with the aid of diaminodiphenyl sulfone, DDS, in stoichiometric proportion. The curing process of the system DGEBA with DDS, in the presence of PET in particular, is monitored applying differential scanning calorimetry, DSC, in isothermal mode. The curing data are used to estimate the temperature regime in a microwave, MW, cavity. Physical confirmations for obtaining sub-micro phase separated DGEBA–DDS–PET composites and, in turn, for efficient modifying of the epoxy phase, have been discussed.

  6. Cure behavior of epoxy polymers used in microelectronics

    Science.gov (United States)

    Taweeplengsangsuke, Jantrawan

    2000-10-01

    Underfill resins are used to reduce solder fatigue in flip-chip assemblies. Both underfilling and curing processes are critical to achieve reliable finished products. This study included two main themes; the development of processing diagrams for commercial underfill resins and the fundamental understanding of cure kinetics and evolution of cure stresses in model epoxies. A variety of techniques have been used to characterize the fundamental phenomena involved in the processing of underfill resins. The flow behavior, cure kinetics, cure stresses, outgassing phenomena and void formation of underfill resins were studied. Processing diagrams for underfill resins were developed by mapping fundamental phenomena involved to provide a guideline for underfilling and curing steps. With these processing diagrams one should be able to design his underfilling and curing process with scientific approach. Two commercial underfill resins, which were evaluated as part of a SEMATECH program, where shown to possess significantly different processing characteristics. However, the appropriate explanation could not be made without knowing the proprietary chemistry of the systems. Therefore, model epoxies were formulated. Three different systems were investigated; amine, imidazole, and anhydride curing agent systems. With the known chemistry, the reaction kinetics and developed cure stress can be explained more clearly. Vitrification, which severely retards the rate of reaction, was found in amine (N-aminoethylpiperazine) and anhydride (Hexahydro-4-methylphthalic anhydride) cured systems when the cure temperatures were lower than the glass transition temperature (T g) of fully cured samples; however, imidazole(2-ethyl-4-methyl-imidazole) did not show vitrification when it was cured at 20 degrees below the T g of fully cured sample due to the large exotherms. Interestingly for imidazole system, the higher cure temperature exhibited a lower Tg. This could possibly be explained by the

  7. Cure SMA

    Science.gov (United States)

    ... SMA Europe and TREAT-NMD for Meeting with EMA Regulators Cure SMA will be participating in a one-day workshop with The European Medicines Agency (EMA—the European equivalent of the FDA), SMA... READ ...

  8. Hydrolysis of Acetic Anhydride in a CSTR

    Directory of Open Access Journals (Sweden)

    Veronica N. Coraci

    2016-05-01

    Full Text Available To find the optimal reactor volume and temperature for the hydrolysis of acetic anhydride at the lowest possible cost with a 90% conversion of acetic anhydride, a formula for the total cost of the reaction was created. Then, the first derivative was taken to find a value for the temperature. This value was then inputted into the second derivative of the equation to find the sign of the value which would indicate whether that point was a minima or maxima value. The minima value would then be the lowest total cost for the optimum reaction to take place.

  9. A New Epoxy-Based Layered Silicate Nanocomposite Using a Hyperbranched Polymer: Study of the Curing Reaction and Nanostructure Development

    Directory of Open Access Journals (Sweden)

    Pilar Cortés

    2014-03-01

    Full Text Available Polymer layered silicate (PLS nanocomposites have been prepared with diglycidyl ether of bisphenol-A (DGEBA epoxy resin as the matrix and organically modified montmorillonite (MMT as the clay nanofiller. Resin-clay mixtures with different clay contents (zero, two, five and 10 wt% were cured, both isothermally and non-isothermally, using a poly(ethyleneimine hyperbranched polymer (HBP, the cure kinetics being monitored by differential scanning calorimetry (DSC. The nanostructure of the cured nanocomposites was characterized by small angle X-ray scattering (SAXS and transmission electron microscopy (TEM, and their mechanical properties were determined by dynamic mechanical analysis (DMA and impact testing. The results are compared with an earlier study of the structure and properties of the same DGEBA-MMT system cured with a polyoxypropylene diamine, Jeffamine. There are very few examples of the use of HBP as a curing agent in epoxy PLS nanocomposites; here, it is found to enhance significantly the degree of exfoliation of these nanocomposites compared with those cured with Jeffamine, with a corresponding enhancement in the impact energy for nanocomposites with the low clay content of 2 wt%. These changes are attributed to the different cure kinetics with the HBP, in which the intra-gallery homopolymerization reaction is accelerated, such that it occurs before the bulk cross-linking reaction.

  10. Ageing of the DGEBA/TETA epoxy system with off-stoichiometric compositions

    Directory of Open Access Journals (Sweden)

    José Roberto Moraes d'Almeida

    2003-06-01

    Full Text Available An investigation was carried out on the room temperature ageing of off-stoichiometric DGEBA/TETA epoxy formulations. The results obtained show that the epoxy rich mixtures have their inherent brittleness increased by the ageing treatment due to recrystalization of the unreacted epoxy monomers, although homopolymerization could also play a minor role. The initial reaction steps dominated by the amine addition reactions control the macromolecular structure and the mechanical performance of the stoichiometric and near stoichiometric formulation with excess of epoxy monomer. Plasticization due to absorbed -OH results on a significant increase of the deformability of these formulations. The amine rich mixtures have the more stable structures, although plasticization due to moisture absorption from the surrounding environment also produces an increase on the deformability of all, but one, of the formulations investigated.

  11. Enthalpy Relaxation of a DGEBA Epoxy as a function of Time, Temperature, and Cooling Rate

    Science.gov (United States)

    Clarkson, Caitlyn M.; McCoy, John D.; Kropka, Jamie M.

    2015-03-01

    Enthalpy relaxation resulting from physical aging of a DGEBA epoxy, Epon 828, cross-linked with an amine curative, Jeffamine T-403, was studied for two isothermal aging temperatures at sequential aging times up to two weeks. Results were analyzed using the peak shift method to obtain the relaxation parameters β, δ (H*), and χ. The individual effects of cooling rate from the equilibrated state, aging time, and aging temperature were isolated to understand the initial state of the glassy epoxy and its evolution during physical aging. [Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  12. DSC and curing kinetics study of epoxy grouting diluted with furfural -acetone slurry

    Science.gov (United States)

    Yin, H.; Sun, D. W.; Li, B.; Liu, Y. T.; Ran, Q. P.; Liu, J. P.

    2016-07-01

    The use of furfural-acetone slurry as active diluents of Bisphenol-A epoxy resin (DGEBA) groutings has been studied by dynamic and non-isothermal DSC for the first time. Curing kinetics study was investigated by non-isothermal differential scanning calorimetries at different heating rates. Activation enery (Ea) was calculated based on Kissinger and Ozawa Methods, and the results showed that Ea increased from 58.87 to 71.13KJ/mol after the diluents were added. The furfural-acetone epoxy matrix could cure completely at the theoretical curing temperature of 365.8K and the curing time of 139mins, which were determined by the kinetic model parameters.

  13. Preparation and characterization of a novel epoxy based nanocomposite using tryptophan as an eco-friendly curing agent

    Energy Technology Data Exchange (ETDEWEB)

    Motahari, Ahmad, E-mail: motahari@umz.ac.ir [Faculty of Chemistry, University of Mazandaran, P.O. Box 453, Babolsar (Iran, Islamic Republic of); Omrani, Abdollah; Rostami, Abbas Ali [Faculty of Chemistry, University of Mazandaran, P.O. Box 453, Babolsar (Iran, Islamic Republic of); Ehsani, Morteza [Iran Polymer and Petrochemical Institute, P.O. Box 14965-115, Tehran (Iran, Islamic Republic of)

    2013-12-20

    Highlights: • Epoxy cured with tryptophan in the presence of 2,4,5-triphenylimidazole. • Kinetic study on the epoxy nanocomposite using advanced isoconversional method. • Structural study and characterization of nanocomposite using SEM, XRD, AFM and DMTA. - Abstract: In this study, kinetics of the curing reaction between DGEBA epoxy resin and tryptophan as an environmentally friendly curing agent in the presence of 2,4,5-triphenylimidazole was reported. The role of silica nanoparticles (SiNP) in changing the mechanism of the curing reaction was also studied. The optimum molar ratio of DGEBA/tryptophan and the optimum content of SiNP were determined by calorimetry analyses. Kinetic analysis using the advanced isoconversional method revealed that the system undergoes the vitrification. Thermogravimetric analysis demonstrated that addition of SiNP does not improve the thermal stability of the tryptophan based thermosets. Impedance spectroscopy and also the standard four-probe method were performed to investigate the effect of curing agent and SiNP loading level on the electrical properties of the cured epoxy. The structure and morphology of the nanocomposite were studied by X-ray diffraction analysis, atomic force microscopy and scanning electron microscopy imaging. Dynamic mechanical thermal analysis revealed that the crosslinking density cannot be significantly affected with the addition of SiNP.

  14. Radiation curing of carbon fibre composites

    Science.gov (United States)

    Spadaro, G.; Alessi, S.; Dispenza, C.; Sabatino, M. A.; Pitarresi, G.; Tumino, D.; Przbytniak, G.

    2014-01-01

    Epoxy/carbon fibre reinforced composites were produced by means of e-beam irradiation through a pulsed 10 MeV electron beam accelerator. The matrix consisted of a difunctional epoxy monomer (DGEBA) and an initiator of cationic polymerisation, while the reinforcement was a unidirectional high modulus carbon fibre fabric. Dynamic mechanical thermal analysis was carried out in order to determine the cross-linking degree. The analysis pointed out a nonuniformity in the cross-linking degree of the e-beam cured panels, with the formation of clusters at low Tg (glass transition temperature) and clusters at high Tg. An out-of-mould post irradiation thermal treatment on e-beam cured samples provides a higher uniformity in the network although some slight degradation effects. Mode I delamination fracture toughness and Interlaminar Shear Strength (ISS) were also investigated by means of Double Cantilever Beam (DCB) and Short Beam Shear tests, respectively. Results from this mechanical characterisation allowed to correlate fracture toughness of the bulk matrix resin, cross-linking density and fibre/matrix interaction to the delamination fracture behaviour of the fibre reinforced material.

  15. PHOTOCOPOLYMERIZATION OF MALEIC ANHYDRIDE AND VINYL ACETATE

    Institute of Scientific and Technical Information of China (English)

    LI Xiaofang; LI Shanjun; QIN Anwei; YU Tongyin

    1990-01-01

    The charge-transfer complex of maleic anhydride and vinyl acetate was copolymerized under UV light. The chain composition and structure of the copolymer were analyzed with conductometry and NMR, and the chain sequence was determined as alternating. The copolymerization rates at different feed ratios, temperatures and in different solvents were investigated, giving evidence to the very active involvement of the CT complexes in the copolymerization. Terpolymerization with acrylonitrile also showed that the complex mechanism was a proper one for this system.

  16. Tannic Acid as a Bio-Based Modifier of Epoxy/Anhydride Thermosets

    Directory of Open Access Journals (Sweden)

    Xiaoma Fei

    2016-08-01

    Full Text Available Toughening an epoxy resin by bio-based modifiers without trade-offs in its modulus, mechanical strength, and other properties is still a big challenge. This paper presents an approach to modify epoxy resin with tannic acid (TA as a bio-based feedstock. Carboxylic acid-modified tannic acid (TA–COOH was first prepared through a simple esterification between TA and methylhexahydrophthalic anhydride, and then used as a modifier for the epoxy/anhydride curing system. Owing to the chemical modification, TA–COOH could easily disperse in epoxy resin and showed adequate interface interaction between TA–COOH and epoxy matrix, in avoid of phase separation. The use of TA–COOH in different proportions as modifier of epoxy/anhydride thermosets was studied. The results showed that TA–COOH could significantly improve the toughness with a great increase in impact strength under a low loading amount. Moreover, the addition of TA–COOH also simultaneously improved the tensile strength, elongation at break and glass transition temperature. The toughening and reinforcing mechanism was studied by scanning electron microscopy (SEM, dynamic mechanical analysis (DMA and thermal mechanical analysis (TMA, which should be owned to the synergistic effect of good interface interaction, aromatic structure, decreasing of cross linking density and increasing of free volume. This approach allows us to utilize the renewable tannic acid as an effective modifier for epoxy resin with good mechanical and thermal properties.

  17. Influence of end groups in hyperbranched polyesters used as modifiers in the characteristics of epoxy thermosets cured by adipic dihydrazide

    Directory of Open Access Journals (Sweden)

    A. Serra

    2013-07-01

    Full Text Available Mixtures of diglycidylether of bisphenol A (DGEBA resin and different ratios of aliphatic-aromatic hyperbranched polyester (HBP were cured by a latent curing agent, adipic dihydrazide (AH. The HBPs prepared have hydroxyl groups or 10-undecenoyl or allyl groups as chain ends. The curing mixtures were investigated by differential scanning calorimetry (DSC to study the curing process and to evaluate the kinetic parameters of the different formulations. These studies suggest that HBPs decrease the curing rate of epoxy/AH in the case of vinyl terminated HPB, whereas OH terminated HBP accelerates the first stages and delays the lasts. The thermosets obtained showed an improvement in microhardness and impact strength without any reduction of the Tg and thermal parameters. Microparticle phase separation was observed with the undecenoyl HBP derivatives or when a 10% of allyl HBP derivative was in the formulation.

  18. Properties of Esterified Wood Prepared with Maleic Anhydride / Tetrabr Omophthalic Anhydride / Glycerol Mixture

    Institute of Scientific and Technical Information of China (English)

    Li Jianzhang; Furuno Takeshi; Zhou Wenrui; Yu Zhiming; Sun Yanling; Zhang Derong

    2003-01-01

    For overcoming disadvantages of wood, an esterification process was employed and tetrabromophthalic anhydride (TBPA) was used as a reactive chemical agent to prepare an esterified wood with the high dimensional stability, flame resistance, and resistance to biodegradation from water-leaching. The experimental results indicated that esterification of wood plus maleic anhydride / tetrabromophthalic anhydride / glycerol could endow wood with dimensional stability, the antiswelling efficiency during water absorption (ASEw), reduction in water absorptivity (RWA), antiswelling efficiency during moisture absorption (ASEm), moisture excluding efficiency (MEE), and oxygen index (OI) of treated wood increased with an increase in the weight percent gain (WPG). And the treated wood showed great decay resistance and resistance to water leaching, too.

  19. Nanofiltration membranes of poly(styrene-co-chloro-methylstyrene)-grafted-DGEBA reinforced with gold and polystyrene nanoparticles for water purification

    Science.gov (United States)

    Kausar, Ayesha; Siddiq, Muhammad

    2015-10-01

    The matrix material for nanofiltration membranes was prepared through chemical grafting of poly(styrene-co-chloromethylstyrene) (PSCMS) to DGEBA using hexamethylenediamine as linker. The phase inversion technique was used to form PSCMS-g-DGEBA membranes. This effort also involves the designing of gold nanoparticles and its composite nanoparticles with polystyrene microspheres as matrix reinforcement. The nanoporous morphology was observed at lower filler content and there was formation of nanopattern at increased nanofiller content. The tensile strength was improved from 32.5 to 35.2 MPa with the increase in AuNPs-PSNPs loading from 0.1 to 1 wt%. The glass transition temperature was also enhanced from 132 to 159 °C. The membrane properties were measured via nanofiltration set-up. Higher pure water permeation flux, recovery, and salt rejection were measured for novel membranes. PSCMS-g-DGEBA/AuNPs-PSNPs membrane with 1 wt% loading showed flux of 2.01 mL cm-2 min-1 and salt rejection ratio of 70.4 %. Efficiency of the gold/polystyrene nanoparticles reinforced membranes for the removal of Hg2+ and Pb2 was found to be 99 %. Novel hybrid membranes possess fine characteristics to be utilized in industrial water treatment units.

  20. Studies on cure kinetics and rheological properties of difunctional epoxy/polysulfone blend system

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.J.; Kim, H.C.; Lee, J.R. [Korean Research Institue of Chemical Technology, Taejeon (Korea)

    2001-03-01

    In this work, the cure kinetics and rheological properties of difunctional epoxy (diglycidylether of bisphenol A, DGEBA)/polysulfone (PSF) blends were investigated using differential scanning calorimeter and rheometer. From the DSC results of the blends, the temperature of the exothermic peak and cure activation energy (E{sub a}) using a half-width method were increased with increasing the PSF content to neat epoxy resin up to 30 wt%. However, a marginal decrease in the blend system was shown in E{sub a}. The conversion ({alpha}) and conversion rate (da/dt) were decreased as the content of PSF increases. Rheological properties of the blend system were investigated under isothermal condition using a rheometer. Cross-linking activation energy (E{sub c}) was determined from the Arrhenius equation based on gel time and curing temperature. As a result, the E-c showed a similar behavior with E{sub a}, which could be resulted from high viscosity of PSF and the phase separation between DGEBA and PSF. (author). 26 refs., 10 figs.

  1. Enhancement in the Glass Transition Temperature in Latent Thiol-Epoxy Click Cured Thermosets

    Directory of Open Access Journals (Sweden)

    Dailyn Guzmán

    2015-04-01

    Full Text Available Tri and tetrafunctional thiol were used as curing agent for diglycidyl ether of bisphenol A (DGEBA catalyzed by a commercially available amine precursor, LC-80. Triglycidyl isocianurate (TGIC was added in different proportions to the mixture to increase rigidity and glass transition temperature (Tg. The cooperative effect of increasing functionality of thiol and the presence of TGIC in the formulation leads to an increased Tg without affecting thermal stability. The kinetics of the curing of mixtures was studied by calorimetry under isothermal and non-isothermal conditions. The latent characteristics of the formulations containing amine precursors were investigated by rheometry and calorimetry. The increase in the functionality of the thiol produces a slight decrease in the storage lifetime of the mixture. The materials obtained with tetrathiol as curing agent showed the highest values of Young’s modulus and Tg.

  2. Advanced Fast Curing Adhesives for Adverse Conditions

    Science.gov (United States)

    2007-07-01

    Figure 2: The reaction of methacrylic acid and DGEBA (Epon 828) to form a partially methacrylated epoxy. 3.2 Methacrylated Epoxy Characterization...is used as a secondary curative in thermosetting polyurethane materials for golf ball covers (18). The solidifier is comprised of DGEBA -epoxy resin

  3. Effects of Different Montmorillonite Nanoclay Loading on Cure Behavior and Properties of Diglycidyl Ether of Bisphenol A Epoxy

    Directory of Open Access Journals (Sweden)

    Alfred Tcherbi-Narteh

    2016-01-01

    Full Text Available The primary focus of this study was to understand the effects of different amounts of montmorillonite nanoclay (MMT loading on viscosity, cure behavior, reaction mechanism, and properties of diglycidyl ether of bisphenol A (DGEBA epoxy composites. Influence of 1–3 wt.% MMT on rheological and subsequent cure behavior of SC-15 epoxy resin was studied using nonisothermal and isothermal rheometry and differential scanning calorimetry (DSC. Rheological properties were influenced by different amounts of MMT at lower shear rates prior to and during curing. Cure reaction mechanism was unaffected by different MMT concentration; however heat and activation energy of reactions increased with increasing MMT loading. Samples with 2 wt.% MMT showed highest reaction rate constant, indicative of catalytic behavior. X-ray diffraction (XRD and transmission electron microscope (TEM revealed mainly intercalated microstructure throughout the MMT infused epoxy composite samples irrespective of the percent loading.

  4. Optimal Composite Curing System

    Science.gov (United States)

    Handel, Paul; Guerin, Daniel

    The Optimal Composite Curing System (OCCS) is an intelligent control system which incorporates heat transfer and resin kinetic models coupled with expert knowledge. It controls the curing of epoxy impregnated composites, preventing part overheating while maintaining maximum cure heatup rate. This results in a significant reduction in total cure time over standard methods. The system uses a cure process model, operating in real-time, to determine optimal cure profiles for tool/part configurations of varying thermal characteristics. These profiles indicate the heating and cooling necessary to insure a complete cure of each part in the autoclave in the minimum amount of time. The system coordinates these profiles to determine an optimal cure profile for a batch of thermally variant parts. Using process specified rules for proper autoclave operation, OCCS automatically controls the cure process, implementing the prescribed cure while monitoring the operation of the autoclave equipment.

  5. PREPARATION OF ISOMERIZED METHYL TETRAHYDROPHTHALIC ANHYDRIDE%异构化甲基四氢苯酐的研制

    Institute of Scientific and Technical Information of China (English)

    吴光杰

    2001-01-01

    Isomerized methyl tetrahydrophthalic anhydride with low viscosity,a curing agent of epoxy resin (N-570D),was prepared in this paper.Effect of some factors,such as catalyst,temperature et al on product gield and method of inhibitting side reaction were also discussed.%制备了低粘度环氧树脂固化剂(N-570D),即:异构化甲基四氢苯酐(MeTHPA),讨论催化剂等因素对收率的影响,并论述了抑制副反应的方法。

  6. Gelatin-based biomaterial engineering with anhydride-containing oligomeric cross-linkers.

    Science.gov (United States)

    Loth, Tina; Hötzel, Rudi; Kascholke, Christian; Anderegg, Ulf; Schulz-Siegmund, Michaela; Hacker, Michael C

    2014-06-01

    Chemically cross-linked gelatin hydrogels are versatile cell-adhesive hydrogel materials that have been established for a variety of biomedical applications. The most prominent cross-linker is glutaraldehyde, which, however, has been described to cause compatibility problems and loss of microscopic but relevant structural features. A recently developed oligomeric cross-linker that contains anhydride functionalities was evaluated as cross-linker for the fabrication of gelatin-based hydrogels and microparticles. In a fast curing reaction, hydrogels composed of gelatin and oligomeric cross-linker were fabricated with good conversion over a wide concentration range of constituents and with cross-linkers of different anhydride contents. Hydrogel properties, such as dry weight and mechanics, could be controlled by hydrogel composition and rheological properties correlated to elastic moduli from 1 to 10 kPa. The gels were shown to be cytocompatible and promoted cell adhesion. In soft formulations, cells migrated into the hydrogel bulk. Gelatin microparticles prepared by a standard water-in-oil emulsion technique were also treated with the novel oligomers, and cross-linking degrees matching those obtained with glutaraldehyde were obtained. At the same time, fewer interparticular cross-links were observed. Fluorescein-derivatized cross-linkers yielded labeled microparticles in a concentration-dependent manner. The oligomeric cross-linkers are presented as an efficient and possibly more functional and compatible alternative to glutaraldehyde. The engineered hydrogel materials hold potential for various biomedical applications.

  7. PRELIMINARY STUDY OF EXTRACTABLE PROTEIN BINDING USING MALEIC ANHYDRIDE COPOLYMER

    Institute of Scientific and Technical Information of China (English)

    Thirawan Nipithakul; Ladawan Watthanachote; Nanticha Kalapat

    2012-01-01

    A preliminary study of using maleic anhydride copolymer for protein binding has been carried out.The polymeric films were prepared by compression of the purified resin and annealing the film to induce efficient back formation of the anhydride groups.The properties of the film surface were analyzed by attenuated total reflection Fourier transforms infrared spectroscopy and water contact angle measurements.The protein content was determined by Bradford assay.To obtain optimum conditions,immersion time for protein binding was examined.Results revealed that proteins can be successfully immobilized onto the film surface via covalent linkage.The efficiency of the covalent binding of the extractable protein to maleic anhydride-polyethylene film was estimated at 69.87 μtg/cm2,although the film had low anhydride content (3%) on the surface.

  8. Statistical deduction and experimental verification on kinetic equations for the curing reactions of epoxy resins/amines

    Institute of Scientific and Technical Information of China (English)

    CHEN Ping; LU Zu-shun; YU Da-shu; HU Li-jiang

    2005-01-01

    Based on three typical mechanisms (second-order, third-order and competitive mechanisms) for the curing reactions of the epoxy resins with amines, a pair of the kinetic equations (for primary and secondary aminations) was presented to explain the uniformity and relationship among the three different kinetic mechanisms of the reactions. The presented macro-equations were deduced from the kinetic micro-equations by the statistics method. And the constitutive equations were verified by experimental data at different reaction times and temperatures (95℃, 60℃ and 39℃), taking diglycidyl ether of bisphenol A (DGEBA) /ethyleneamine (EA) as a model.

  9. Effects of Surface Treatments of Montmorillonite Nanoclay on Cure Behavior of Diglycidyl Ether of Bisphenol A Epoxy Resin

    Directory of Open Access Journals (Sweden)

    Alfred Tcherbi-Narteh

    2013-01-01

    Full Text Available Diglycidyl ether of Bisphenol A (DGEBA based SC-15 epoxy resin was modified with three different commercially available montmorillonite (MMT nanoclay: Nanomer I.28E and Cloisite 10A and 30B. Cure behavior of nanocomposites was studied using a variety of techniques. Primary focus of this study was to investigate influence of different surface modifications of MMT nanoclay on rheological properties and cure behavior of SC-15 epoxy resin. By adding MMT to SC-15 epoxy resin, chemistry of the epoxy is altered leading to changes in rheological properties and ultimately enthalpy and activation energy of reactions. Addition of Nanomer I.28E delayed gelation, while Cloisite 10A and 30B accelerated gelation, regardless of the curing temperature. Activation energy of reaction was lower with the addition of Nanomer I.28E and Cloisite 10A and higher for Cloisite 30B compared to neat SC-15 epoxy composite.

  10. PDMS-modified poly(styrene-alt-maleic anhydride)s as water-borne coatings based on surfactant-free latexes

    NARCIS (Netherlands)

    Gunbas, I.D.; Wouters, M.E.L.; Benthem, R.A.T.M. van; Koning, C.E.; Noordover, B.A.J.

    2013-01-01

    In this work, two series of PDMS-modified poly(styrene-alt-maleic anhydride)s (PSMA) were prepared by the partial imidization of their anhydride groups with mono-functional, amine-terminated polydimethyl siloxanes (PDMS-NH2) with two different molecular weights. Subsequently, surfactant-free artific

  11. 磷酸化EVOH/DGEBA/PPA交联质子交换膜的研究%Research on Phosphorylated EVOH/DGEBA/PPA Cross-linked Proton Exchange Membranes

    Institute of Scientific and Technical Information of China (English)

    王姝珊; 翟良芳; 刘剑洪; 李翠华; 管蓉

    2013-01-01

    为了研究适用于高温低湿环境下的燃料电池质子交换膜,本文采用了一种新型交联试剂双酚A二缩水甘油醚型环氧树脂(DGEBA),按照一定配比对乙烯-乙烯醇的嵌段共聚物(EVOH)进行适度交联,引入多聚磷酸(PPA)对交联膜进行磷酸化,制备了磷酸化EVOH/DGEBA/PPA交联膜.通过傅里叶红外(FTIR)、X射线衍射(XRD)和质子电导率等测试对膜的性能进行了表征.实验结果表明:所制备的膜成功地进行了交联反应和磷酸化反应;交联反应使膜的热稳定性和氧化稳定性得到改善;随磷酸化时间的增加,膜的离子交换容量值和电导率增加,但氧化稳定性有所降低.在相对湿度为60%时,膜的质子电导率要高于Nafion膜,所研制的膜有望在高温低湿环境下的质子交换膜燃料电池中使用.

  12. Strain Rate Dependence of Compressive Yield and Relaxation in DGEBA Epoxies

    Science.gov (United States)

    Arechederra, Gabriel K.; Reprogle, Riley C.; Clarkson, Caitlyn M.; McCoy, John D.; Kropka, Jamie M.; Long, Kevin N.; Chambers, Robert S.

    2015-03-01

    The mechanical response in uniaxial compression of two diglycidyl ether of bisphenol-A epoxies were studied. These were 828DEA (Epon 828 cured with diethanolamine (DEA)) and 828T403 (Epon 828 cured with Jeffamine T-403). Two types of uniaxial compression tests were performed: A) constant strain rate compression and B) constant strain rate compression followed by a constant strain relaxation. The peak (yield) stress was analyzed as a function of strain rate from Eyring theory for activation volume. Runs at different temperatures permitted the construction of a mastercurve, and the resulting shift factors resulted in an activation energy. Strain and hold tests were performed for a low strain rate where a peak stress was lacking and for a higher strain rate where the peak stress was apparent. Relaxation from strains at different places along the stress-strain curve was tracked and compared. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  13. Addition effect of erbium(III) trifluoromethanesulfonate in the homopolymerization kinetics of a DGEBA resin

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, S.J. [Area de Ciencia de los Materiales, Departament d' Enginyeria de Sistemes Industrials i Disseny, Universitat Jaume I, Avda. Vicent Sos Baynat s/n, 12071 Castellon (Spain)]. E-mail: espallar@sg.uji.es; Ramis, X. [Laboratori de Termodinamica, Escola Tecnica Superior Enginyeria Industrial Barcelona, Universitat Politecnica de Catalunya, Diagonal 647, 08028 Barcelona (Spain); Serra, A. [Departament de Q. Analitica i Q. Organica, Facultat de Quimica, Universitat Rovira i Virgili, C/Marcel.li Domingo s/n, 43007 Tarragona (Spain); Suay, J. [Centro de Biomateriales, Universitat Politecnica de Valencia, Camino de Vera s/n, E-46071 Valencia (Spain)

    2006-02-01

    Solid bisphenol-A epoxy resin of medium molecular weight was cured using a Lewis acid initiator (erbium(III) trifluoromethanesulfonate) in three different proportions (0.5, 1 and 2 phr). A kinetic study was performed in a differential scanning calorimeter. The complete kinetic triplet was determined (activation energy, pre-exponential factor, and integral function of the deg.ree of conversion) for each system. A kinetic analysis was performed with an integral isoconversional procedure (model-free), and the kinetic model was determined both with the Coats-Redfern method (the obtained isoconversional E value being accepted as the effective activation energy) and through the compensation effect. All the systems followed the same isothermal curing model simulated from non-isothermal ones. The 'nucleation and growth' Avrami kinetic model A {sub 3/2} has been proposed as the polymerization kinetic model. The addition of initiator accelerated the reaction having higher influence when low temperatures were applied.

  14. The characteristics of epoxy resin cured by {gamma}-ray and E-beam

    Energy Technology Data Exchange (ETDEWEB)

    Nho, Y.C. E-mail: ycnho@kaeri.re.kr; Kang, Phil Hyun; Park, Jong Seok

    2004-10-01

    Epoxy resins are widely used as high-performance thermosetting resins for many industrial applications. In this study, the effect of an electron beam (E-beam) and {gamma}-ray irradiation on the curing of epoxy resins was investigated. Diglycidyl ether of bisphenol-A(DGEBA), diglycidyl ether of bisphenol-F(DGEBF) as epoxy resins, triarylsulfonium hexafluoroantimonate(TASHFA), and triarylsulfonium hexafluorophosphate(TASHFP) as initiators were used in this study. The chemical and mechanical characteristics of irradiated epoxy resins were compared after curing of E-beam and {gamma}-ray irradiation up to 50 kGy in N{sub 2} and air atmosphere. We ascertained the effect of oxygen on the radiation curing of epoxy resin. The thermal properties of cured epoxy were investigated using DMA and TGA. Mechanical properties such as flexural strength were measured. The chemical structures of cured epoxy were characterized by FT-NIR. The gel fraction and the stress at yield of epoxy resins irradiated by E-beam and {gamma}-ray in N{sub 2} atmosphere were also compared with those of epoxy resins irradiated by E-beam and {gamma}-ray in air.

  15. Curing kinetics and morphology of a nanovesicular epoxy/stearyl-block-poly(ethylene oxide) surfactant system.

    Science.gov (United States)

    Bogaerts, K; Lavrenova, A; Spoelstra, A B; Boyard, N; Goderis, B

    2015-08-21

    Brittle epoxy based thermosets can be made tougher by introducing structural inhomogeneities at the micro- or nanoscale. In that respect, nano vesicles and worm-like micelles from self-assembling blockcopolymers have been shown to be very effective. This paper describes the curing kinetics and morphology of an epoxy composed of diglycidyl ether of bisphenol A (DGEBA) and 4,4'-methylenedianiline (MDA), modified by 20% of the surfactant stearyl-block-poly(ethylene oxide). Time resolved, synchrotron small-angle X-ray scattering demonstrates that at any time during the epoxy curing process, the surfactant predominantly adopts a bilayer vesicular nano-morphology. Transmission electron microscopy on fully cured systems reveals the coexistence of spherical and worm-like micelles. Differential scanning calorimetry experiments prove that the presence of surfactant reduces the epoxy curing rate but that ultimately full curing is accomplished. The material glass transition temperature falls below that of the pure resin due to plasticization. It is suggested that favorable secondary interactions between the PEO segments and the epoxy resin are responsible for the observed phenomena.

  16. Curing Behavior of Epoxy Asphalt

    Institute of Scientific and Technical Information of China (English)

    YU Jianying; CONG Peiliang; WU Shaopeng; CHENG Songbo

    2009-01-01

    The curing process of epoxy asphalt was analyzed by Fourier transform infrared (FT-IR)spectroscopy.Effect of curing temperature on viscosity of epoxy asphalt,and changes of mechanical properties with curing time were investigated.The evolution of concentration of epoxy band was followed as a function of the applied curing process.The experimental results indicate that the curing reaction rate of epoxy asphalt is invariable before 70 min at 120℃,and it decreases when curing time exceeds 70 min.The viscosity of epoxy asphalt increases slowly with curing time at initial curing stage.But it increases quickly after initial curing stage and the initial curing time decreases as the curing temperature increases.The tensile strength increases slowly at incipient curing stage and increases rapidly when curing time is form 20 min to 70 min.The elongation at break shows a decrease with curing time,but it exceeds 200%after cured.

  17. Radiation curing of epoxies

    Science.gov (United States)

    Dickson, Lawrence W.; Singh, Ajit

    The literature on radiation polymerization of epoxy compounds has been reviewed to assess the potential use of radiation for curing these industrially important monomers. Chemical curing of epoxies may proceed by either cationic or anionic mechanisms depending on the nature of the curing agent, but most epoxies polymerize by cationic mechanisms under the influence of high-energy radiation. Radiation-induced cationic polymerization of epoxy compounds is inhibited by trace quantities of water because of proton transfer from the chain-propagating epoxy cation to water. Several different methods with potential for obtaining high molecular weight polymers by curing epoxies with high-energy radiation have been studied. Polymeric products with epoxy-like properties have been produced by radiation curing of epoxy oligomers with terminal acrylate groups and mixtures of epoxies with vinyl monomers. Both of these types of resin have good potential for industrial-scale curing by radiation treatment.

  18. 改性脂肪族胺类环氧树脂固化剂:非等温固化反应%Modified Aliphatic Amine Curing Agent for Epoxy Resin Non-Isothermal Curing Reaction

    Institute of Scientific and Technical Information of China (English)

    张予东; 王艳萍; 张静; 刘恒; 毛立群

    2016-01-01

    The non-isothermal curing reaction of the modification of aliphatic amines (DTP)/bisphenol A diglycidyl ether (DGEBA)system was investigated by using differential scanning calorimetry (DSC)method.The results indicate that the reaction is an exothermic process,and only one single and fairly symmetric exothermic peak can be found,which corresponds to the opening reaction of epoxy amine.The relationship between the effective activation energy and the conversion rate was established with Flynn-Wall-Ozawa (FWO)model.It is found that the reaction is similar to other epoxy resin systems following the same rules.In the initial stage,the system has the highest effective activation energy, while the effective activation energy decreases gradually as the reaction proceeds. Furthermore,the reaction rate model was determined as Šesták-Berggren (SB(m ,n ))empirical model according to the characteristic parameters of the model ofαM 、αp 、α∞p ,and the kinetics properties of the reaction was confirmed by Málek model.The simulated model discloses that the reaction is of autocatalytic characteristic,and the calculated reaction rates are in good agreement with the experimental values.The research on the curing reaction of DTP/DGEBA system contributes to the understanding of the reaction mechanism and the condition,and provides a reference for the selection of DTP/ DGEBA curing process.%采用 DSC 法研究了改性脂肪族胺(DTP)/双酚 A 二缩水甘油醚(DGEBA)体系的非等温固化过程,结果表明,该固化反应是一个放热过程,且仅有一个对称的放热峰,对应于环氧胺开环加成反应。采用 Flynn-Wall-Ozawa (FWO)模型关联活化能 E α与转化率α的关系,结果显示,该固化反应显示出与其他环氧树脂体系类似的反应规律。在反应开始时,该系统具有最高的表观活化能;但随着反应的进行,表观活化能逐渐降低。利用 Málek 模型研究该固化反应的动力学性质,

  19. Epoxy/anhydride thermosets modified with end-capped star polymers with poly(ethyleneimine cores of different molecular weight and poly(ε–caprolactone arms

    Directory of Open Access Journals (Sweden)

    C. Acebo

    2015-09-01

    Full Text Available Multiarm star polymers, with a hyperbranched poly(ethyleneimine (PEI core and poly(ε-caprolactone (PCL arms end-capped with acetyl groups were synthesized by ring-opening polymerization of ε-caprolactone from PEI cores of different molecular weight. These star polymers were used as toughening agents for epoxy/anhydride thermosets. The curing process was studied by calorimetry, thermomechanical analysis and infrared spectroscopy. The final properties of the resulting materials were determined by thermal and mechanical tests. The addition of the star polymers led to an improvement up to 130% on impact strength and a reduction in the thermal stresses up to 55%. The structure and molecular weight of the modifier used affected the morphology of the resulting materials. Electron microscopy showed phase-separated morphologies with nano-sized fine particles well adhered to the epoxy/anhydride matrix when the higher molecular weight modifier was used.

  20. Study of the structure and the mechanical properties of dynamically cured PP/MAH-g-SEBS/epoxy blends

    Institute of Scientific and Technical Information of China (English)

    Xue Liang Jiang; Yin Xi Zhang

    2009-01-01

    A new method concerning with the simultaneous reinforcing and toughening of polypropylene (PP) was reported. Dynamical cure of the epoxy resin was successfully applied in the PP/maleic anhydride-grafted styrene--ethylene-butylene-styrene (SEBS) triblock copolymer, and the obtained blends named as dynamically cured PP/MAH-g-SEBS/epoxy blends. The stiffness and toughness of the blends are in a good balance, and MAH-g-SEBS was acted as not only an impact modifier but also a compatibilizer. The structure of the dynamically cured PP/MAH-g-SEBS/epoxy blends is the embedding of the epoxy particles by the MAH-gSEBS.

  1. Magnetic Resonance Studies of Epoxy Resins.

    Science.gov (United States)

    1980-12-07

    cyclohexanedicarboxylic anhydride (CHCA) with tripropylamine (TPA), and the MY720 was cured with DDH. The calculated stoichiometric mixtures for the systems ...investigate main-chain molecular motions in the epoxy resins tetraglycidyldiaminodiphenylmethane (TGDDM) and diglycidyl ether of bisphenol A (DGEBA) cured ...elimination reaction to release a stable nitroxide spin probe. In the dry cured epoxy resins at each temperature, the EPR lineshapes of the spin labels

  2. Power and Thermal Technology for Air and Space. Delivery Order 0006: Nano-filled Polymers for Electrical Insulation

    Science.gov (United States)

    2006-10-01

    T. Kvarts, “Increasing the Electrical Discharge Endurance of Acid Anhydride Cured DGEBA Epoxy Resin by Dispersion of Nanoparticle Silica,” High...56 pbw Jeffamine D-400. This resin systems gels at room temperature over the course of several hours. A thermal post cure cycle is used to complete...the cure . A B Figure 1: Chemical structures of the resin system components used in this study: A) EPON 828 (n=0.3), and B

  3. The Curing Meter

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    2006-01-01

    Curing technology concerns adjustment and control of temperature and moisture conditions in hardening structures and elements of concrete. The curing technology comprises e.g. measurement, adjustment and control of the moisture conditions during the early hardening phase of the concrete to achiev...... from concrete surfaces in the early hardening phase. The Concrete Curing Meter is designed for simple and reliable monitoring of water loss from a wet surface of fresh concrete. This new measuring technique has been tested with several prototypes of the Curing Meter.......Curing technology concerns adjustment and control of temperature and moisture conditions in hardening structures and elements of concrete. The curing technology comprises e.g. measurement, adjustment and control of the moisture conditions during the early hardening phase of the concrete to achieve...... an optimal development of properties in the hardening concrete – so-called "moisture curing". Proper moisture curing is vital to concrete but laborious to accomplish and difficult to control at the construction site with present methods. This paper concerns a new method for site measurement of evaporation...

  4. Kinetic study of polymerization/curing of filament-wound composite epoxy resin systems with aromatic diamines

    Science.gov (United States)

    Golub, M. A.; Lerner, N. R.; Hsu, M. S.

    1986-01-01

    The kinetics of polymerization/curing of a filament-wound composite epoxy resin consisting of an 80/20 DGEBA/DGEBD blend and an MDA/m-PDA blend (Tonox 60/40) was studied at various temperatures and at amine epoxy ratios between 1.1 and 4.4 by means of Fourier-transform (FT) IR and bulk viscosity measurements. The activation energy for the polymerization/curing reaction using an amine/epoxy ratio of 1.1 was 11.9 kcal/mole, in agreement with a previous value. The FT-IR conversion-time plots were fitted to a kinetic expression containing two rate constants with activation energies of 13.7 and 10.0 kcal/mole. The bulk viscosity followed the Williams et al. (1955) equation, with a Di Benedetto (1965) expression for the glass transition temperature.

  5. Quantitative Analysis of Curing Mechanisms of Epoxy Resin by Mid- and Near- Fourier Transform Infra Red Spectroscopy

    Directory of Open Access Journals (Sweden)

    Sagar T. Cholake

    2014-05-01

    Full Text Available This article informs the essence of major work done by a number of researchers on the analysis of two-step curing mechanism of diglycidyl ether of bisphenol A (DGEBA epoxy resin in presence of amine curing agents using near- and mid-IR technology. Various peaks used as a marker for resin formation are discussed and their implementation is comprehensively studied. In addition to this, a wide range of information about the importance of reference peaks in both near-IR (NIR and mid-IR (MIR regions are congregated and their accuracy is audited. Also discrepancies observed by researchers in epoxy conversion (α in NIR and MIR regions are reviewed to highlight the comparative advantages of both regions, one over the other.Defence Science Journal, Vol. 64, No. 3, May 2014, pp. 314-321, DOI:http://dx.doi.org/10.14429/dsj.64.7326

  6. Thermal degradation and evolved gas analysis: A polymeric blend of urea formaldehyde (UF and epoxy (DGEBA resin

    Directory of Open Access Journals (Sweden)

    Tansir Ahamad

    2014-12-01

    Full Text Available A polymeric blend has been prepared using urea formaldehyde (UF and epoxy (DGEBA resin in 1:1 mass ratio. The thermal degradation of UF/epoxy resin blend (UFE was investigated by using thermogravimetric analyses (TGA, coupled with FTIR and MS. The results of TGA revealed that the pyrolysis process can be divided into three stages: drying process, fast thermal decomposition and cracking of the sample. There were no solid products except ash content for UFE during combustion at high temperature. The total mass loss during pyrolysis at 775 °C is found to be 97.32%, while 54.14% of the original mass was lost in the second stage between 225 °C and 400 °C. It is observed that the activation energy of the second stage degradation during combustion (6.23 × 10−4 J mol−1 is more than that of pyrolysis (5.89 × 10−4 J mol−1. The emissions of CO2, CO, H2O, HCN, HNCO, and NH3 are identified during thermal degradation of UFE.

  7. Radiation curing of {gamma}-Al{sub 2}O{sub 3} filled epoxy resin

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Phil Hyun; Kim, Dong Jin; Nho, Young Chang [KAERI, Taejon (Korea, Republic of)

    2003-10-01

    Epoxy resins are widely utilized as high performance thermosetting resins for many industrial applications but characterized by a relatively low toughness. Recently, the incorporation with rigid inorganic was suggested to improve the mechanical properties of epoxy resins. In the present work, an attempt has been taken to disperse nano-sized {gamma}- Al{sub 2}O{sub 3} particles into diglycidyl ether of bisphenol-A (DGEBA) epoxy resins for improvement of the mechanical properties. These hybrid epoxy-alumina composites were prepared using by the {gamma}-ray curing technique that was conducted with 100kGy under nitrogen at room temperature. The composites were characterized by determining gel content, UTM (Instron model 4443), SEM, FT-IR studies.

  8. Thermal properties and fracture toughness of difunctional epoxy resins cured by catalytic initiators

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.J.; Heo, G.Y.; Lee, J.R. [Korea Research Institute of Chemical Technology, Taejon (Korea)

    2002-05-01

    In this work, two thermal cationic latent catalysts, i.e., triphenyl benzyl phosphonium hexafluoroantimonate (TBPH) and benzyl 2-methylpyrazinium hexaluoroantimonate (BMPH) were newly synthesized. And the thermal and mechanical properties of difunctional epoxy (diglycidylether of bisphenol A, DGEBA) resins initiated by 1 phr of either TBPH or BMPH catalyst were investigated. As experimental results, the epoxy/TBPH system showed higher curing temperature and critical stress intensity factor (K{sub 1C}) than those of epoxy/BMPH. This could be interpreted in terms of slow thermal diffusion rate and bulk structure of four phenyl groups in TBPH. However, the decomposed activation energy determined from Coats-Redfern method was lower in the case of epoxy/TBPH. This result was probably due to the fact that broken short chain structure was developed by steric hindrance of TBPH. (author). 24 refs., 3 tabs., 6 figs.

  9. C-CURE

    Data.gov (United States)

    US Agency for International Development — C-CURE system manages certain aspects of the access control system, including collecting employee and contractor names and photographs. The Office of Security uses...

  10. Microwave-assisted addition of azomethines to isatoic anhydride

    Indian Academy of Sciences (India)

    E Dominic Jacob; Lopez Mathew; Baby Thomas

    2007-01-01

    Diels-Alder addition of azomethines to isatoic anhydride in a solvent-free and eco-friendly condition is investigated using a microwave oven. The product is exclusively 2,3-diaryl-2,3-dihydroquinazolin-4(1H)-ones 4a-d. HOMO-LUMO energy of the iminoketene and the dienophiles were calculated using semi-empirical AM1 calculations.

  11. CHARACTERIZATION AND THERMAL STABILITY OF PMR POLYIMIDES USING 7-OXA-BICYCLO[2,2,1]HEPT-5-ENE-2, 3-DICARBOXYLIC ANHYDRIDE AS END CAPS

    Institute of Scientific and Technical Information of China (English)

    Chen-liang Gong; Yan-feng Li; Hai-xia Yang; Xiao-long Wang; Shu-jiang Zhang; Shi-yong Yanga

    2011-01-01

    An anhydride monomer containing ether oxide bridge,7-oxa-bicyclo[2,2,1]hept-5-ene-2,3-dicarboxylic anhydride (ONA),was successfully synthesized by Diels-Alder reaction of furan and maleic anhydride.The ONA was also studied as an end-cap for the polymerization of monomer reactant (PMR) type polyimides.Three molecular weight levels of the ONA end-capped PMR resins were evaluated.The effects of process conditions of these novel PMR resins on thermal and mechanical properties were investigated.It was demonstrated that the imidized prepolymers using the end-cap have good processability,and the cured polyimide specimens exhibited good thermal stability.The initial decomposition temperature,Td (ca.580℃) and glass transition temperature,Tg (330℃) of the novel resin (PI-20),prepared under optimum process conditions,compare favorably with the Td (ca.620℃) and Tg (ca.348℃) of the state-of-the-art resin (PI'-20),respectively.

  12. Blends of nitrile butadiene rubber/poly (vinyl chloride: The use of maleated anhydride castor oil based plasticizer

    Directory of Open Access Journals (Sweden)

    Indiah Ratna Dewi

    2016-06-01

    Full Text Available Recently, much attention has been focused on research to replace petroleum-based plasticizers, with biodegradable materials, such as biopolymer which offers competitive mechanical properties. In this study, castor oil was modified with maleic anhydride (MAH to produce bioplasticizer named maleated anhydride castor oil (MACO, and used in nitrile butadiene rubber (NBR/poly vinyl chloride (PVC blend. The effect of MACO on its cure characteristics and mechanical properties of NBR/PVC blend has been determined. The reactions were carried out at different castor oil (CO/xylene ratios, i.e. 1:0 and 1:1 by weight, and fixed CO/MAH ratio, 1:3 by mole. DOP, CO, and MACO were added into each NBR/PVC blend according to the formula. It was found that the viscosity and safe process level of NBR/PVC blend is similar from all plasticizer, however, MACO (1:0 showed the highest cure rate index (CRI. MACO-based plasticizer gave a higher value of the mechanical properties of the NBR/PVC blend as compared to DOP based plasticizer. MACO (1:1 based plasticizer showed a rather significance performance compared to another type of plasticizers both before and after aging. The value of hardness, elongation at break, tensile strength, and tear strength were 96 Shore A, 155.91 %, 19.15 MPa, and 74.47 MPa, respectively. From this result, NBR/PVC blends based on MACO plasticizer can potentially replace the DOP, and therefore, making the rubber blends eco-friendly.

  13. Radiation curing in the eighties

    Energy Technology Data Exchange (ETDEWEB)

    Vrancken, A. (UCB, Drogenbos (Belgium). Chemical Specialities Div.)

    1984-05-01

    The subject is discussed under the headings: introduction; what is radiation curing; history; radiation curable resins (with properties of products); ultraviolet and electron beam curing; photoinitiation and the ultraviolet light curing process; electron beam curing (initiation; electron beam accelerators); end uses (graphic arts; wood finishing; paper upgrading; adhesives; metal finishing; electronic chemical; floor coatings).

  14. Intrinsic Flame-Retardant and Thermally Stable Epoxy Endowed by a Highly Efficient, Multifunctional Curing Agent

    Directory of Open Access Journals (Sweden)

    Chunlei Dong

    2016-12-01

    Full Text Available It is difficult to realize flame retardancy of epoxy without suffering much detriment in thermal stability. To solve the problem, a super-efficient phosphorus-nitrogen-containing reactive-type flame retardant, 10-(hydroxy(4-hydroxyphenylmethyl-5,10-dihydrophenophosphazinine-10-oxide (HB-DPPA is synthesized and characterized. When it is used as a co-curing agent of 4,4′-methylenedianiline (DDM for curing diglycidyl ether of bisphenol A (DGEBA, the cured epoxy achieves UL-94 V-0 rating with the limiting oxygen index of 29.3%. In this case, the phosphorus content in the system is exceptionally low (0.18 wt %. To the best of our knowledge, it currently has the highest efficiency among similar epoxy systems. Such excellent flame retardancy originates from the exclusive chemical structure of the phenophosphazine moiety, in which the phosphorus element is stabilized by the two adjacent aromatic rings. The action in the condensed phase is enhanced and followed by pressurization of the pyrolytic gases that induces the blowing-out effect during combustion. The cone calorimeter result reveals the formation of a unique intumescent char structure with five discernible layers. Owing to the super-efficient flame retardancy and the rigid molecular structure of HB-DPPA, the flame-retardant epoxy acquires high thermal stability and its initial decomposition temperature only decreases by 4.6 °C as compared with the unmodified one.

  15. CURING KINETICS AND THERMAL STABILITY OF EPOXY BLENDS CONTAINING PHOSPHOROUS-OXIRANE WITH AROMATIC AMIDE-AMINE AS CURING AGENTS

    Institute of Scientific and Technical Information of China (English)

    Geeta Durga; A.K.Narula

    2012-01-01

    This article describes the synthesis of a series of aromatic amide-amines and their potential use as epoxy hardeners.These amines were synthesized by the reaction of L-phenylalanine (PA) with diamines of different structures i.e.1,4-phenylene diamine (PD),1,5-diamino naphthalene (N),4,4′-(9-fluorenyllidene)-dianiline (F),4,4′-diaminodiphenyl sulphide (DS) and 3,4′-oxydianiline (O) in a stoichiometric ratio (1∶1).Structural characterization of synthesized amide-amines was done with the help of elemental analysis and spectroscopic techniques viz.FT-IR,1H-NMR and 13C-NMR.An epoxy blend was prepared by mixing tris(glycidyloxy) phosphine oxide (TGPO) with conventional epoxy i.e.diglycidyl ether of bisphenol-A (DGEBA) in an equivalent ratio of 2∶3 to incorporate phosphorous into the main chain.The curing kinetics of the epoxy blend with synthesized aromatic amide-amines was investigated by non-isothermal DSC technique using multiple heating rate method (5,10,15 and 20 K/min.).The activation energies were determined by fitting the experimental data into Kissinger and Ozawa kinetic models.The activation energies obtained through Ozawa method were slightly higher than those of Kissinger method but were comparable.However,both the energies were found to be dependent on the structure of amines.The thermal stability and weight loss behavior of isothermally cured thermosets were also investigated using thermogravimetric analysis (TGA) in nitrogen atmosphere.All the samples showed improved thermal stability in terms of char yield than using only amines as hardeners.

  16. Dual cure photocatalyst systems

    Energy Technology Data Exchange (ETDEWEB)

    DeVoe, R.J.; Brown-Wensley, K.A.; Holmes, G.L.; Mathis, M.D.; McCormick, F.B.; Palazzotto, M.C.; Spurgeon, K.M. (Minnesota Mining and Mfg. Co., St. Paul, MN (USA). Corporate Research Labs.)

    1990-01-01

    A family of dual cure photocatalyst systems is being developed to be used in the solventless processing of organic coatings. The photocatalyst systems consist of organometallic compounds often in combination with other agents. Upon photolysis, the photocatalyst system generates a Lewis acid and a free radical. The Lewis acid can initiate the polymerization of epoxies or the addition of isocyanates and polyols to form polyurethanes while the free radical can initiate the polymerization of acrylates. The performance of the various photocatalyst systems will be compared on the basis of the physical properties of the cured compositions they produce. 17 figs.

  17. 含磷固化剂及固化环氧树脂的合成及表征%Synthesis and Characterization of Phosphorus-Containing Curing Agent and Cured Epoxy Resins

    Institute of Scientific and Technical Information of China (English)

    张靓靓; 许凯; 陈鸣才; 曹现福; 陈德宏

    2006-01-01

    以4,4'-二氨基二苯基甲烷(DDM)、苯甲醛和亚磷酸二乙酯为原料,合成了两种含磷固化剂PM1和PM2,用红外光谱、核磁共振氢谱对PM1和PM2的结构进行了表征.用DDM,PM1,PM2分别固化双酚A型(DGEBA)环氧树脂,得到DGEBA-DDM,DGEBA-PM1,DGEBA-PM2树脂,采用示差扫描量热法、热重分析(TGA)和极限氧指数(LOI)对DGEBA-DDM,DGEBA-PM1,DGEBA-PM2树脂的玻璃化转变温度(Tg)、反应活性、热稳定性和阻燃性能进行了表征.实验结果表明,PM2的反应活性比PM1低;DGEBA-DDM,DGEBA-PM1,DGEBA-PM2树脂的Tg分别为178,112,145 ℃;TGA结果表明,700 ℃时DGEBA-PM1和DGEBA-PM2树脂的成炭率分别为29%和35%,而700 ℃时DGEBA-DDM树脂的成炭率只有19%;DGEBA-PM1和DGEBA-PM2树脂的LOI值由DGEBA-DDM树脂的24%分别增至30%和35%,且阻燃性能大幅度提高.

  18. Curing the queue

    NARCIS (Netherlands)

    Zonderland, Maartje Elisabeth

    2012-01-01

    In this dissertation we study several problems related to the management of healthcare and the cure of disease. In each chapter a hospital capacity distribution problem is analyzed using techniques from operations research, also known as mathematical decision theory. The problems considered are insp

  19. Curing Kinetics and Thermal Stability of Diglycidyl Ether of Bisphenol-A Using Mixtures of Heterocyclic Derivatives of Stannanes and 4,4'-Diaminodiphenylsulfone

    Institute of Scientific and Technical Information of China (English)

    SINGH Vikram; DEEP Gagan; NARULA Anudeep Kumar

    2008-01-01

    Curing kinetics of diglycidyl ether of bisphenol-A (DGEBA) in the presence of varying molar ratios of derivafives of stannanes to 4,4'-diaminodiphenylsulfone (DDS) was investigated by the dynamic differential scanning calorimetry. The derivatives were synthesized by reacting 1 mole of biguanide (B) with 1 mole of phenylethyltindihydride (PETH) or phenylmethyltindihydride (PMTH) or phenylbutyltindihydride (PBTH) and designated as BPETH or BPMTH or BPBTH respectively. These derivatives were characterized by elemental analysis and spectroscopic techniques such as IR, 1H NMR, 13C NMR and 119Sn NMR. The mixtures of these derivatives to DDS at of epoxy resins. The thermal stability of the isothermally cured resins was also evaluated using dynamic thermogravimetry in a nitrogen atmosphere.

  20. Thermal Degradation of DGEBA/EDA Epoxy Resin%双酚A缩水甘油醚/乙二胺环氧树脂的热分解行为

    Institute of Scientific and Technical Information of China (English)

    丁宏博; 张剑秋; 蔡培

    2011-01-01

    采用傅里叶红外光谱法研究了双酚A缩水甘油醚/乙二胺环氧树脂(DGEBA/EDA)在不同温度时分解残留物的红外吸收光谱;利用热分析技术考察了DGEBA/EDA从室温到600℃之间的热解反应.结果表明,DGEBA/EDA环氧树脂在氮气中分解时存在一个热解阶段,最低热解活化能为195.74 kJ/mol.色谱-质谱联用(GC/MS)分析DGEBA/EDA环氧树脂热解残留物,表明在热解过程中主要生成苯酚、对异丙基苯酚和双酚A.讨论了DGEBA/EDA环氧树脂热解的机理.经热解后的残留环氧树脂的热稳定性降低明显,环氧树脂发生了明显的化学裂解.%The thermal degradation behaviors of diglycidyl ethers of bisphenol A /ethylenediamine (DGEBA/EDA) epoxy resin in N2 atmosphere were investigated by using thermogravimetry(TG) analysis from 25 ℃ to 600 ℃. The TG results show that DGEBA/EDA epoxy resin has only one degradation step, the lowest activation energy is 195.74 kJ/mol. The gaseous pyrolysis products were collected and characterized by gas chromatography-mass spectrometry (CC/MS) and their formation was discussed. The main pyrolysis products were phenol, pisopropylphenol and bisphenol-A. The thermal degradation mechanism of DGEBA/EDA epoxy resin was discussed.The TG analysis of raw materials and solid epoxy resin product shows that the thermal stability of the resin reduces significantly after the degradation. The molecular weight of the solid product decreases and its degree of polymerization of epoxy resin is below the raw materials.

  1. A facile and efficient synthetic method for 4-phenylethynylphthalic anhydride

    Institute of Scientific and Technical Information of China (English)

    Di Feng Wu; Mei Jia Yang; Yang Wang; Guo Wei Gao; Jian Men

    2011-01-01

    A novel approach to the synthesis of 4-phenylethynylphthalic anhydride has been described. The target compound was synthesized by Pd/Cu catalyzed Sonogashira coupling reaction between phenylacetylene and 4-bromophthalic acid which was for the first time employed as start material, followed by dehydration of 4-phenylethynylphthalic acid. Compared with traditional synthetic routes, this method provides several advantages such as readily available raw materials, convenient manipulation and high yield. The products were characterized by IR, 1H NMR, 13C NMR, MS and elemental analysis, respectively.

  2. Synthesis and curing of alkyd enamels based on ricinoleic acid

    Directory of Open Access Journals (Sweden)

    Jovičić Mirjana C.

    2010-01-01

    Full Text Available A combination of an alkyd resin with a melamine-formaldehyde resin gives a cured enamel film with the flexibility of the alkyd constituent and the high chemical resistance and hardness of the melamine resin at the same time. The melamine resin is a minor constituent and plays the role of a crosslinking agent. In this paper, alkyd resins of high hydroxyl numbers based on trimethylolpropane, ricinoleic acid and phthalic anhydride were synthesized. Two alkyds having 30 and 40 wt% of ricinoleic acid were formulated by calculation on alkyd constant. Alkyds were characterized by FTIR and by the determination of acid and hydroxyl numbers. Then synthesized alkyds were made into baking enamels by mixing with melamine-formaldehyde resins (weight ratio of 70:30 based on dried mass. Two types of commercial melamine resins were used: threeisobutoxymethyl melamine-formaldehyde resin (TIMMF and hexamethoxymethyl melamine resin (HMMMF. Prepared alkyd/melamine resin mixtures were cured in a differential scanning calorimeter (DSC under non-isothermal mode. Apparent degree of curing as a function of temperature was calculated from the curing enthalpies. Kinetic parameters of curing were calculated using Freeman-Carroll method. TIMMF resin is more reactive with synthesized alkyds than HMMMF resin what was expected. Alkyd resin with 30 wt% of ricinoleic acid is slightly more reactive than alkyd with 40 wt% of ricinoleic acid, probably because it has the high contents of free hydroxyl and acid groups. The gel content, Tg, thermal stability, hardness, elasticity and impact resistance of coated films cured at 150°C for 60 min were measured. Cured films show good thermal stability since the onset of films thermal degradation determined by thermogravimetric analysis (TGA is observed at the temperatures from 281 to 329°C. Films based on alkyd 30 are more thermal stable than those from alkyd 40, with the same melamine resin. The type of alkyd resin has no significant

  3. 腰果酚二醚曼尼希碱固化剂的合成及其相分离现象研究%Synthesis and Phase Separation Phenomena of Cardanol Diethers-Mannich Base Curing Agent

    Institute of Scientific and Technical Information of China (English)

    宋健; 李梅; 李守海; 黄坤; 夏建陵

    2016-01-01

    The cardanol diethers (CDE) was obtained from Williamson etherification of cardanol(CD) and 1,3-dibromopropane.Then the cardanol diethers-Mannich baseas curing agent (MBCDE) for epoxy resins was prepared from the Mannich reaction of CDE, paraformadehyde and diethylenetriamine.The chemical structure was confirmed by FT-IR and 1H NMR.N-Aminoethylpiperazine (AEP) was chose as a control to investigate the toughening properties of MBCDE.Thermogravimetric analysis (TGA), scanning electronic microscopy (SEM) and mechanical properties of the cured epoxies were also conducted to investigate the properties of the bisphenol A epoxy resin (DGEBA) cured by two curing agents.The TGA results showed that the maximum decomposition temperature of MBCDE was 351.6 ℃ and the sample had good thermal stability.The impact strength of cured AEP/DGEBA was 3.641 J/m, while the cured 80% MBCDE sample had an impact strength of 5.155 J/m, which was improved by 41.6%.SEM results indicated that there was phase seperation in the cured materials contained MBCDE.%腰果酚(CD)和1,3-二溴丙烷经Williamson醚化反应得到一种腰果酚二醚化合物(CDE),然后以CDE、多聚甲醛和二乙烯三胺为原料,经Mannich反应制备得到一种浅色的腰果酚二醚曼尼希碱固化剂(MBCDE).通过傅里叶红外光谱(FT-IR)和核磁共振氢谱(1H NMR)表征了产物的化学结构,并与氨乙基哌嗪(AEP)进行对比研究其相关性能.通过热重分析(TGA)、扫描电镜(SEM)和力学性能测试研究了两种固化剂与双酚A环氧树脂(DGEBA)固化材料的相关性能.结果表明:MBCDE/DGEBA的最大分解温度为351.6 ℃,具有良好的热稳定性.AEP/DGEBA环氧固化物的冲击强度为3.641 J/m,而添加80%的MBCDE后固化物的冲击强度则为5.155 J/m,提高了41.6%.SEM分析结果表明MBCDE固化材料中存在相分离.

  4. Telechelic polyisobutylene with unsaturated end groups and with anhydride end groups

    NARCIS (Netherlands)

    Walch, E.; Gaymans, R.J.

    1994-01-01

    Anhydride terminated polyisobutylene (PIB) oligomers were synthesized in a one- or two-step process from chlorine terminated oligomers. In the one-step process, chlorine functional oligomers were just heated in the presence of maleic anhydride (MA) for 12 h at 190°C without a catalyst. In the two-st

  5. MALEIC ANHYDRIDE HYDROGENATION OF PD/AL2O3 CATALYST UNDER SUPERCRITICAL CO2 MEDIUM

    Science.gov (United States)

    Hydrogenation of maleic anhydride (MA) to either y-butyrolactone of succinic anhydride over simple Pd/Al2O3 impregnated catalyst in supercritical CO2 medium has been studied at different temperatures and pressures. A comparison of the supercritical CO2 medium reaction with the c...

  6. Investigations on organolead compounds III. The reaction of organolead compounds with ketene. (Triphenylplumbyl)acetic anhydride

    NARCIS (Netherlands)

    Willemsens, L.C.; Kerk, G.J.M. van der

    1965-01-01

    The reaction of ketene with triphenyllead hydroxide in diethyl ether gave (triphenylplumbyl)acetic anhydride, (Ph3PbCH2CO)2O, the first anhydride-substituted organolead compound known. The reaction of ketene with triphenyllead acetate in absolute ethanol gave ethyl (triphenylplumbyl)acetate, Ph3PbCH

  7. Modification of wheat starch with succinic acid/acetic anhydride and azelaic acid/acetic anhydride mixtures I. Thermophysical and pasting properties.

    Science.gov (United States)

    Subarić, Drago; Ačkar, Durđica; Babić, Jurislav; Sakač, Nikola; Jozinović, Antun

    2014-10-01

    The aim of this research was to investigate the influence of modification with succinic acid/acetic anhydride and azelaic acid/acetic anhydride mixtures on thermophysical and pasting properties of wheat starch. Starch was isolated from two wheat varieties and modified with mixtures of succinic acid and acetic anhydride, and azelaic acid and acetic anhydride in 4, 6 and 8 % (w/w). Thermophysical, pasting properties, swelling power, solubility and amylose content of modified starches were determined. The results showed that modifications with mixtures of afore mentioned dicarboxylic acids with acetic anhydride decreased gelatinisation and pasting temperatures. Gelatinisation enthalpy of Golubica starch increased, while of Srpanjka starch decreased by modifications. Retrogradation after 7 and 14 day-storage at 4 °C decreased after modifications of both starches. Maximum, hot and cold paste viscosity of both starches increased, while stability during shearing at high temperatures decreased. % setback of starches modified with azelaic acid/acetic anhydride mixture decreased. Swelling power and solubility of both starches increased by both modifications.

  8. 40 CFR 721.6183 - Amides, from ammonium hydroxide - maleic anhydride polymer and hydrogenated tallow alkyl amines...

    Science.gov (United States)

    2010-07-01

    ... - maleic anhydride polymer and hydrogenated tallow alkyl amines, sodium salts, compds. with ethanolamine... Substances § 721.6183 Amides, from ammonium hydroxide - maleic anhydride polymer and hydrogenated tallow... anhydride polymer and hydrogenated tallow alkyl amines, sodium salts, compds. with ethanolamine (PMN...

  9. Evaluation of copolymer conformation states of vinylchloride-maleic anhydride

    Science.gov (United States)

    Ivanov, A. A.

    2016-11-01

    The quantum-chemical analysis and experimental study of alternating vinylchloride-maleic anhydride (VC-MA) copolymer macromolecules with polymerization degree 600 have been carried out. The VC-MA copolymer in solvents of different nature undergoes cycloanhydride-enol tautomerism and the macromolecules take the form of corrugated sticks according to viscometric measurements. The computer simulation has shown that the segment with polymerization degree n < 18 (model compound) is not a helix and rolls while if n = 18 the conformations get distorted. The model molecule optimal structure comprising a random sequence of alternating units of comonomers and their enol tautomers with minimal system total energy has been found by the semiempirical parametric method PM3.

  10. Acetylation of barnyardgrass starch with acetic anhydride under iodine catalysis.

    Science.gov (United States)

    Bartz, Josiane; Goebel, Jorge Tiago; Giovanaz, Marcos Antônio; Zavareze, Elessandra da Rosa; Schirmer, Manoel Artigas; Dias, Alvaro Renato Guerra

    2015-07-01

    Barnyardgrass (Echinochloa crus-galli) is an invasive plant that is difficult to control and is found in abundance as part of the waste of the paddy industry. In this study, barnyardgrass starch was extracted and studied to obtain a novel starch with potential food and non-food applications. We report some of the physicochemical, functional and morphological properties as well as the effect of modifying this starch with acetic anhydride by catalysis with 1, 5 or 10mM of iodine. The extent of the introduction of acetyl groups increased with increasing iodine levels as catalyst. The shape of the granules remained unaltered, but there were low levels of surface corrosion and the overall relative crystallinity decreased. The pasting temperature, enthalpy and other gelatinisation temperatures were reduced by the modification. There was an increase in the viscosity of the pastes, except for the peak viscosity, which was strongly reduced in 10mM iodine.

  11. Modeling HIV Cure

    Science.gov (United States)

    Perelson, Alan; Conway, Jessica; Cao, Youfang

    A large effort is being made to find a means to cure HIV infection. I will present a dynamical model of post-treatment control (PTC) or ``functional cure'' of HIV-infection. Some patients treated with suppressive antiviral therapy have been taken off of therapy and then spontaneously control HIV infection such that the amount of virus in the circulation is maintained undetectable by clinical assays for years. The model explains PTC occurring in some patients by having a parameter regime in which the model exhibits bistability, with both a low and high steady state viral load being stable. The model makes a number of predictions about how to attain the low PTC steady state. Bistability in this model depends upon the immune response becoming exhausted when over stimulated. I will also present a generalization of the model in which immunotherapy can be used to reverse immune exhaustion and compare model predictions with experiments in SIV infected macaques given immunotherapy and then taken off of antiretroviral therapy. Lastly, if time permits, I will discuss one of the hurdles to true HIV eradication, latently infected cells, and present clinical trial data and a new model addressing pharmacological means of flushing out the latent reservoir. Supported by NIH Grants AI028433 and OD011095.

  12. A fully coupled diffusion-reaction scheme for moisture sorption-desorption in an anhydride-cured epoxy resin

    KAUST Repository

    El Yagoubi, Jalal

    2012-11-01

    Thermoset materials frequently display non-classical moisture sorption behaviors. In this paper, we investigated this issue from an experimental point of view as well as in terms of modeling the water transport. We used the gravimetric technique to monitor water uptake by epoxy samples, with several thicknesses exposed to different levels of humidity during absorption and desorption tests. Our results revealed that the polymer displays a two-stage behavior with a residual amount of water that is desorbed progressively. We proposed a phenomenological reaction-diffusion scheme to describe this behavior. The model describes water transport as a competition between diffusion and the reaction, during which the local diffusivity and solubility depend on the local advancement of the reaction. We then implemented our model using COMSOL Multiphysics and identified it using a MATLAB-COMSOL optimization tool and the experimental data. We discussed the relation between the hydrophilicity of the product of the reaction and the diffusion behavior. We examined the reaction-induced modification of the water concentration field. It is worth noting that part of the phenomenology can be explained by the presence of hydrolyzable groups. © 2012 Elsevier Ltd. All rights reserved.

  13. Synthesis and cure mechanism characterization of phenylethynyl-terminated imide oligomers

    Science.gov (United States)

    Back, Susanna Branion

    Polymer matrix composites (PMC) are being investigated by the Air Force for use in engine applications, which are comprised of an intermediate carbon fiber-reinforced high temperature phenylethynyl-terminated fluorinated polyimide resin. The high-temperature phenylethynyl-terminated fluorinated polyimide resin is prepared from 4-(phenylethynyl)phthalic anhydride (4-PEPA), p-phenylenediamine (p-PDA), and hexafluoroisopropylidene bisphthalic dianhydride (6FDA). In order for these materials to be exploited to their full potential, many fundamental aspects of the polymer system need to be better understood. For this study, the high-temperature cure mechanism, the chemical structures of cure reaction products, and the effect of physical properties of impurities in the 4-PEPA monomer were investigated. A phenylethynyl-terminated imide model compound, N-(3-phenoxybenzene)-4-phenylethynylphthalimide (N-PBPEP), was prepared using both industrial 4-PEPA and recrystallized 4-PEPA. The thermal cure of this low molecular weight compound was studied using a variety of analytical techniques including differential scanning calorimetry, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), and mass spectrometry (MS). N-PBPEP made from industrial 4-PEPA begins curing 25°C later than N-PBPEP made from recrystallized 4-PEPA, indicating that thermal cure is affected by the purity of the 4-PEPA starting material. Also, both versions form an 830 g/mol dimer with three possible mechanistic pathways.

  14. Immediate and delayed allergy from epoxy resins based on diglycidyl ether of bisphenol A.

    Science.gov (United States)

    Kanerva, L; Jolanki, R; Tupasela, O; Halmepuro, L; Keskinen, H; Estlander, T; Sysilampi, M L

    1991-06-01

    This case report presents two patients with immediate and delayed allergy to epoxy resins based on diglycidyl ether of bisphenol A (DGEBA). In patch testing, the epoxy resin (DGEBA-based) of the standard series gave allergic reactions. Both patients had a prick test reaction of histamine size or larger to the human serum albumin (HSA) conjugate of DGEBA-based epoxy resins. One had been occupationally exposed to methyl tetrahydrophthalic anhydride (MTHPA) and had a histamine-size prick test reaction to the HSA conjugate of MTHPA; the other did not react to the conjugate. Determinations of specific immunoglobulin E were carried out with HSA-DGEBA conjugates, two DGEBA-based epoxy resins, and phthalic anhydrides. The first patient had positive tests to DGEBA, the DGEBA-based epoxy resins, and two phthalic anhydrides, and the second to DGEBA and the DGEBA-based epoxy resins, but not to the phthalic anhydrides.

  15. Curing mechanism of TDE-85/MeTHPA epoxy resin modified by polyurethane

    Institute of Scientific and Technical Information of China (English)

    LI Zhi-hua; ZHENG Zi-qiao; REN Dong-yan; HUANG Yao-peng

    2007-01-01

    Diglycidyl 4,5-epoxy tetrahydro phthalate/methyl tetrahydrophthalic anhydride (TDE-85/MeTHPA) epoxy resin modified by polyurethane (PU) was prepared with 1,4-butanediol (1,4-BDO), trimethylol propane (TMP) and polyurethane prepolymer synthesized by polypropylene glycol and toluene diisocynate. Chemical reaction and curing mechanism of this system were discussed by incorporating the results of infra spectrum analysis. The results indicate that the epoxy polymeric network Ⅰ is obtained by the curing reaction between TDE-85 and MeTHPA, while the PU polymeric network Ⅱ is obtained by the chain-extended and crosslinking reaction between 1,4-BDO, TMP and polyurethane prepolymer(PUP). The graft chemical bonds are formed between polymer networks Ⅰ and Ⅱ that therefore increase the degree of blend and compatibility between epoxy polymer and PU.

  16. Investigation of Plasma Polymerized Maleic Anhydride Film in a Middle Frequency Dielectric Barrier Discharge

    Institute of Scientific and Technical Information of China (English)

    TANG Wenjie; CHEN Qiang; ZHANG Yuefei; GE Yuanjing

    2008-01-01

    Plasma polymerized maleic anhydride (MA) was carried out by using maleic anhydride supersaturated ethanol solution as a precursor in a dielectric barrier discharge (DBD). The film properties were characterized by water contact angle (WCA), Fourier transfer infrared (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM) analysis, and a thickness profilometer. The influence of the processing parameters on the film properties such as the power frequency, and polymerization zone was investigated. The results show that anhydride group incorporated into the growing films is favorable at the frequency of 80 kHz and working pressure of 50 Pa. The poly (maleic anhydride) film is uniform and compact at an average deposition rate of 8 nm/min.

  17. Highly efficient peptide formation from N-acetylaminoacyl-AMP anhydride and free amino acid

    Science.gov (United States)

    Mullins, D. W., Jr.; Lacey, J. C., Jr.

    1983-01-01

    The kinetics of formation of the N-blocked dipeptide, N-acetylglycylglycine, from N-acetylglycyl adenylate anhydride and glycine in aqueous solution at 25 C, and at various PH's are reported. The reaction is of interest in that over a physiologically relevant pH range (6-8), peptide synthesis proceeds more rapidly than hydrolysis, even at those pH's at which this compound becomes increasingly susceptible to base-catalyzed hydrolysis. Under similar conditions, the corresponding unblocked aminoacyl adenylate anhydrides are considerably more unstable, and undergo appreciable hydrlysis in the presence of free amino acid. Because N-blocked aminoacyl adenylate anhydrides serve as model compounds of peptidyl adenylate anhydrides, these results suggest that primitive amino acid polymerization systems may have operated by cyclic reactivation of the peptidyl carboxyl group, rather than that of the incoming amino acid.

  18. Graft Copolymers of Maleic Anhydride and Its Isostructural Analogues: High Performance Engineering Materials

    OpenAIRE

    Rzayev, Zakir M. O.

    2011-01-01

    This review summarizes the main advances published over the last 15 years outlining the different methods of grafting, including reactive extruder systems, surface modification, grafting and graft copolymerization of synthetic and natural polymers with maleic anhydride and its isostructural analogues such as maleimides and maleates, and anhydrides, esters and imides of citraconic and itaconic acids, derivatives of fumaric acid, etc. Special attention is spared to the grafting of conventional ...

  19. Determination of the Preferred Structure, Dynamics, and Planarity of Substituted Anhydrides by Cp-Ftmw

    Science.gov (United States)

    McMahon, Timothy J.; Bailey, Josiah R.; Bird, Ryan G.; Pratt, David

    2016-06-01

    The planarity of five-membered rings is derived from a competition between ring-angle strain and stability of the torsional angles. The planar form maximizes the already stressed, smaller-than-normal, C-C bond angles, while puckering reduces the unfavorable eclipsed interactions. The structure, dynamics, and planarity of three anhydrides, succinic, methylsuccinic, and methylene (itaconic) anhydride, were studied and compared using chirped-pulse Fourier transform microwave spectroscopy.

  20. Controversies in HIV cure research

    Directory of Open Access Journals (Sweden)

    Johnston Rowena

    2012-03-01

    Full Text Available Abstract Background Antiretroviral therapy significantly reduces HIV viral burden and prolongs life, but does not cure HIV infection. The major scientific barrier to a cure is thought to be the persistence of the virus in cellular and/or anatomical reservoirs. Discussion Most efforts to date, including pharmaco, immuno or gene therapy, have failed to cure patients, with the notable exception of a stem cell transplant recipient commonly known as the Berlin patient. This case has revived interest in the potential to cure HIV infection and has highlighted the need to resolve critical questions in the basic, pre-clinical and clinical research spheres as they pertain specifically to efforts to eradicate HIV from the body of an infected person (a sterilizing cure or at least render the need for lifelong antiretroviral therapy obsolete (functional cure. This paper describes ongoing debates in each of these research spheres as they were presented and discussed at a satellite session that took place at the 6th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention in Rome in July 2011. Summary The resolution of these debates may have important implications for the search for a cure, the most efficient ways to identify and test promising interventions, and ultimately the availability of such a cure to diverse groups of HIV patients around the world.

  1. Réaction du polyisobutène chloré sur l'anhydride maléique : mécanisme. Catalyse par l'anhydride dichloromaléique Reaction of Chlorinated Polyisobutene on Maleic Anhydride. Mechanism. Catalysis by Dichloromaleic Anhydride

    Directory of Open Access Journals (Sweden)

    Sillion B.

    2006-11-01

    Full Text Available Dans cet article le mécanisme de la réaction de condensation du polyisobutène chloré sur l'anhydride maléique, qui sert dans la synthèse d'additif pour lubrifiant, est étudié par une cinétique globale et par un travail sur composés modèles. Il est montré que, dans cette réaction, l'anhydride maléique joue un double rôle : de catalyseur de déshydrochloration par une réactivité de type acide de Lewis organique, de réactif comme diénophile. Grâce à ces résultats, il est proposé une catalyse par l'anhydride dichloromaléique, qui permet une amélioration sensible du procédé. This article examines the mechanism of the chlorinated-polyisobutene condensation reaction on maleic anhydride. The overall kinetics and model compounds are investigated for this reaction which is used in the synthesis of lubricant additives. Maleic anhydride is shown to play the dual role of a dehydrochlorination catalyst by having a reactivity of the organic Lewis acid type and of a reactant like dienophile. These results are used to propose a catalysis by dichloromaleic anhydride which appreciably improves the process.

  2. CURING EFFICIENCY OF DUAL-CURE RESIN CEMENT UNDER ZIRCONIA WITH TWO DIFFERENT LIGHT CURING UNITS

    Directory of Open Access Journals (Sweden)

    Pınar GÜLTEKİN

    2015-04-01

    Full Text Available Purpose: Adequate polymerization is a crucial factor in obtaining optimal physical properties and a satisfying clinical performance from composite resin materials. The aim of this study was to evaluate the polymerization efficiency of dual-cure resin cement cured with two different light curing units under zirconia structures having differing thicknesses. Materials and Methods: 4 zirconia discs framework in 4 mm diameter and in 0.5 mm, 1 mm and 1.5 mm thickness were prepared using computer-aided design system. One of the 0.5 mm-thick substructures was left as mono-layered whereas others were layered with feldspathic porcelain of same thickness and ceramic samples with 4 different thicknesses (0.5, 1, 1.5 and 2.0 mm were prepared. For each group (n=12 resin cement was light cured in polytetrafluoroethylene molds using Light Emitting Diode (LED or Quartz-Tungsten Halogen (QHT light curing units under each of 4 zirconia based discs (n=96. The values of depth of cure (in mm and the Vickers Hardness Number values (VHN were evaluated for each specimen. Results: The use of LED curing unit produced a greater depth of cure compared to QTH under ceramic discs with 0.5 and 1 mm thickness (p<0.05.At 100μm and 300 μm depth, the LED unit produced significantly greater VHN values compared to the QTH unit (p<0.05. At 500 μm depth, the difference between the VHN values of LED and QTH groups were not statistically significant. Conclusion: Light curing may not result in adequate resin cement polymerization under thick zirconia structures. LED light sources should be preferred over QTH for curing dual-cure resin cements, especially for those under thicker zirconia restorations.

  3. Vegetable oil-derived epoxy monomers and polymer blends: A comparative study with review

    OpenAIRE

    T. P. Schuman; Wang, R.

    2013-01-01

    Glycidyl esters of epoxidized fatty acids derived from soybean oil (EGS) and linseed oil (EGL) have been synthesized to have higher oxirane content, more reactivity and lower viscosity than epoxidized soybean oil (ESO) or epoxidized linseed oil (ELO). The EGS and ESO, for comparison, were used neat and in blends with diglycidyl ether of bisphenol A (DGEBA). Thermosetting resins were fabricated with the epoxy monomers and either BF3 catalyst or anhydride. The curing behaviors, glass transition...

  4. Immunosuppression of the Trimellitic Anhydride-Induced Th2 Response by Novel Nonanatural Products Mixture in Mice

    Directory of Open Access Journals (Sweden)

    Min-Jung Bae

    2013-01-01

    Full Text Available Many natural dietary products prevent or cure allergic inflammation; however, the ability of mixtures of these natural medicinals to suppress allergic skin inflammation is unknown. We examined the inhibitory effects of nonanatural products mixture (NPM-9, which provides immunoregulatory activation, on Th2-mediated skin allergic inflammation. Oral administration of NPM-9 in mice reduced ear thickness and specific IgE production in trimellitic anhydride- (TMA-induced contact hypersensitivity (CHS. NPM-9 also suppressed IL-4 and IL-1β production in splenocytes but prevented only TMA-induced IL-1β production in inflamed ears. To characterize the mechanism of this effect, we examined NPM-9 immunosuppression on an OVA-induced Th2 allergic state. Oral administration of NPM-9 inhibited Th2-mediated serum IgE overproduction. NPM-9 also downregulated the polarized Th2 response, whereas it upregulated Th1 response in splenocytes. These data suggest that NPM-9 may be a useful therapeutic agent for allergic inflammatory diseases through its suppression of the Th2-mediated allergic response.

  5. Selective hydrogenation of maleic anhydride over Pd/Al2O3 catalysts prepared via colloid deposition

    Indian Academy of Sciences (India)

    Hongjing Yuan; Chunlei Zhang; Weitao Huo; Chunli Ning; Yong Tang; Yi Zhang; Dequan Cong; Wenxiang Zhang; Jiahuan Luo; Su Li; Zhenlu Wang

    2014-01-01

    Pd/Al2O3 catalysts were prepared via colloid deposition and the performance of the catalysts was examined in the selective hydrogenation of maleic anhydride to succinic anhydride. When the reaction was carried on in a batch system with 1,4-dioxane as the solvent (353K and 1.0MPa), high conversion of maleic anhydride (>98%) and high selectivity (>99%) for succinic anhydride were observed after 5 h. The as-prepared Pd/Al2O3 catalyst also showed excellent performance in solvent-free system and fixed-bed systems. The maleic anhydride (MA) conversion was greater than 98%, and high selectivity (>99%) for succinic anhydride was obtained after 1600 h in a fixed bed reacter. The results showed that the activity of the Pd/Al2O3 catalysts was excellent due to its high active surface area.

  6. Novel techniques for concrete curing

    DEFF Research Database (Denmark)

    Kovler, Konstantin; Jensen, Ole Mejlhede

    2005-01-01

    It is known that some high-strength/high-performance concretes (HSC/HPC) are prone to cracking at an early age unless special precautions are taken. The paper deals with the methods of curing as one of the main strategies to ensure good performance of concrete. Curing by both external (conventional......) and internal methods is reviewed and analyzed, among other methods of mitigating shrinkage and cracking of concrete. The focus is on the mitigation of autogenous shrinkage of low water to binder ratio (w/b) concrete by means of internal curing. The concepts of internal curing are based on using lightweight...... aggregate, superabsorbent polymers or water-soluble chemicals, which reduce water evaporation (so called "internal sealing"). These concepts have been intensively researched in the 90s, but still are not widespread among contractors and concrete suppliers. The differences between conventional methods...

  7. Correlation of cure monitoring techniques

    Science.gov (United States)

    Chang, S. S.; Mopsik, F. I.; Hunston, D. L.

    Six different composite matrix or neat resin cure-monitoring methods are presently used to follow the cure process in a model epoxy system, and the results obtained are compared. Differential scanning calorimetry, viscosity monitoring, the ultrasonic shear wave propagation technique, dielectric spectrometry, and two different fluorescence intensity techniques are compared with a view to common traits and differences. Dielectric fluorescence and ultrasonic measurement techniques are noted to be applicable to on-line process monitoring.

  8. Characterization and Curing Kinetics of Epoxy/Silica Nano-Hybrids

    Directory of Open Access Journals (Sweden)

    Cheng-Fu Yang

    2015-10-01

    Full Text Available The sol-gel technique was used to prepare epoxy/silica nano-hybrids. The thermal characteristics, curing kinetics and structure of epoxy/silica nano-hybrids were studied using differential scanning calorimetry (DSC, 29Si nuclear magnetic resonance (NMR and transmission electron microscopy (TEM. To improve the compatibility between the organic and inorganic phases, a coupling agent was used to modify the diglycidyl ether of bisphenol A (DGEBA epoxy. The sol-gel technique enables the silica to be successfully incorporated into the network of the hybrids, increasing the thermal stability and improving the mechanical properties of the prepared epoxy/silica nano-hybrids. An autocatalytic mechanism of the epoxy/SiO2 nanocomposites was observed. The low reaction rate of epoxy in the nanocomposites is caused by the steric hindrance in the network of hybrids that arises from the consuming of epoxide group in the network of hybrids by the silica. In the nanocomposites, the nano-scale silica particles had an average size of approximately 35 nm, and the particles were well dispersed in the epoxy matrix, according to the TEM images.

  9. The Role of Boundary Layer Capacitance at Blocking Electrodes in the Interpretation of Dielectric Cure Data in Adhesives.

    Science.gov (United States)

    1984-05-31

    Microdielectrometry, dielectric constant, epoxy resins, DGEBA , conduc:ivi:v-, permittivity, loss factor, polarization, blocking layer. 20. A@STRACT...larger than the actual bulk permittivity of the matetal under measurement. Data are presented which demonstrate this effect with a DGEBA resin in the...with a DGEBA resin in the presence of blocking layers that vary in thickness from .0023 to 1.5 pm. The implications for the interpretation of data

  10. Curing units' ability to cure restorative composites and dual-cured composite cements under composite overlay.

    Science.gov (United States)

    Park, Sung-Ho; Kim, Su-Sun; Cho, Yong-Sik; Lee, Chang-Kyu; Noh, Byng-Duk

    2004-01-01

    This study compared the efficacy of using conventional low-power density QTH (LQTH) units, high-power density QTH (HQTH) units, argon (Ar) laser and Plasma arc curing (PAC) units for curing dual-cured resin cements and restorative resin composites under a pre-cured resin composite overlay. The microhardness of the two types of restorative resins (Z100 and Tetric Ceram) and a dual-cured resin cement (Variolink II) were measured after they were light cured for 60 seconds in a 2 mm Teflon mold. The recorded microhardness was determined to be the optimum microhard-ness (OM). Either one of the two types of restorative resins (Z100, Tetric Ceram) or the dual cured resin cement (Variolink II) were placed under a 1.5-mm thick and 8 mm diameter pre-cured Targis (Vivadent/Ivoclar AG, Schaan, Liechtenstein) overlay. The specimens that were prepared for each material were divided into four groups depending upon the curing units used (HQTH, PAC, Laser or LQTH) and were further subdi-vided into subgroups according to light curing time. The curing times used were 30, 60, 90 and 120 seconds for HQTH; 12, 24, 36 and 48 seconds for the PAC unit; 15, 30, 45 and 60 for the Laser and 60, 120 or 180 seconds for the LQTH unit. Fifteen specimens were assigned to each sub- group. The microhardness of the upper and and lower composite surfaces under the Targis overlay were measured using an Optidur Vickers hardness-measuring instrument (Göttfert Feinwerktechnik GmbH, Buchen, Germany). In each material, for each group, a three-way ANOVA with Tukey was used at the 0.05 level of significance to compare the microhardnesses of the upper and lower composite surfaces and the previously measured OM of the material. From the OM of each material, 80% OM was calculated and the time required for the microhardness of the upper and lower surface of the specimen to reach 100% and 80% of OM was determined. In Z100 and Tetric Ceram, when the composites were light cured for 120 seconds using the HQTH lamp

  11. Cold-Curing Structural Epoxy Resins: Analysis of the Curing Reaction as a Function of Curing Time and Thickness

    Directory of Open Access Journals (Sweden)

    Carola Esposito Corcione

    2014-09-01

    Full Text Available The curing reaction of a commercial cold-curing structural epoxy resin, specifically formulated for civil engineering applications, was analyzed by thermal analysis as a function of the curing time and the sample thickness. Original and remarkable results regarding the effects of curing time on the glass transition temperature and on the residual heat of reaction of the cold-cured epoxy were obtained. The influence of the sample thickness on the curing reaction of the cold-cured resin was also deeply investigated. A highly exothermal reaction, based on a self-activated frontal polymerization reaction, was supposed and verified trough a suitable temperature signal acquisition system, specifically realized for this measurement. This is one of the first studies carried out on the curing behavior of these peculiar cold-cured epoxy resins as a function of curing time and thickness.

  12. Synthesis, characterization and cure kinetics of polyaniline modified MMT clay/epoxy nanocomposites

    Science.gov (United States)

    Aykanat, Aydin

    bisphenol-A (DGEBA) epoxy prepolymer crosslinked with tri ethylene tetra amine (TETA) was analyzed by DSC. The tensile, flexural and impact tests of carbon fiber epoxy micro composites showed that PANi coated carbon fiber epoxy systems have higher modulus, toughness and mechanical strengths compared to unmodified carbon fiber epoxy composites. In the second part of the research work, conducting polyaniline (PANi) montmorillonite (MMT) clay nanocomposites were synthesized by using in-situ polymerization. The X-Ray diffraction patterns showed that polyaniline was intercalated between clay galleries in the order of nanoscale. From the SEM micrographs, it was revealed that, in-situ polymerization of aniline took place both in and out of the clay galleries. Polyaniline surface modified clay nanoparticles were then dispersed in diglycidyl ether of bisphenol-A (DGEBA) epoxy prepolymer using high shear mixing and ultrasonication. The viscosity measurements of modified and unmodified clay dispersed in epoxy prepolymer systems showed that PANi modified clay has lower viscosity than the pristine clay that provides easiness during processing. Infrared spectroscopy data proves that reactive secondary and tertiary amine groups on the fully dispersed polyaniline modified clay platelets react with epoxy resin resulting a strong chemical and physical interaction between nanoparticles and polymeric matrix. The effect of PANi surface modified nano particles on the curing reaction and kinetics of epoxy with tri-ethylene tetra amine (TETA) was analyzed by using DSC and explained by modified Avrami equation. The X-Ray diffraction pattern of fully cured 5% (w/w) PANi-MMT clay epoxy nanocomposites showed exfoliation behavior. Thermal analysis showed that for 5% (w/w) PANi-MMT filled epoxy nanocomposites has higher thermal stability than both fully cured pristine epoxy and 5% (w/w) clay epoxy nanocomposite. With the addition and exfoliation of 5% (w/w) PANi modified clay an increase of 8°C in

  13. Selective oxidation of carbon monoxide in the presence of butane and maleic anhydride

    Energy Technology Data Exchange (ETDEWEB)

    Corbin, D.R.; Bonifaz, C. (DuPont Company, Wilmington, DE (United States))

    1994-03-01

    The selective oxidation of carbon monoxide in the presence of butane and maleic anhydride has been studied over platinum- and palladium-containing zeolites as well as palladium-on-silica (Pd/SiO[sub 2]) catalysts. The results show that although a zeolite support is needed in many systems to effect a kinetic control to improve selectivity, thermodynamic control using Pd([approximately]2-4 ppm)/SiO[sub 2] is sufficient to give the desired selectivities in this system. In addition, a palladium-containing vanadium-phosphate catalyst was prepared that showed complete oxidation of carbon monoxide, conversion of butane to maleic anhydride, and no observable decomposition of the maleic anhydride. 14 refs., 4 tabs.

  14. Collagen functionalized with unsaturated cyclic anhydrides-interactions in solution and solid state.

    Science.gov (United States)

    Potorac, S; Popa, M; Picton, L; Dulong, V; Verestiuc, L; Le Cerf, D

    2014-03-01

    Maleic anhydride (CMA) and itaconic anhydride modified collagen (CITA) were prepared as precursors for production of interpenetrated polymer networks (IPN). Calculated values for Huggins coefficient in aqueous diluted and semi-diluted solutions of modified collagen indicated a slightly tendency of aggregation for itaconic anhydride-modified collagen. In semi-diluted solution collagen (Coll) and CMA present slightly differences in the thixotropic behavior, while CITA has a pronounced thixotropic behavior. Flow and oscillatory measurements revealed an elastic behavior of the collagen solutions, pure and modified with MA or ITA, as the storage modulus (G') has always a superior value compared with the loss modulus (G″). The denaturation temperature (Td) of unmodified collagen increased from 34°C to 40°C for CMA and to 39°C for CITA respectively, by formation of covalent bonds that stabilize the triple helix.

  15. Synthesis of first row transition metal carboxylate complexes by ring opening reactions of cyclic anhydrides

    Indian Academy of Sciences (India)

    Jubaraj Bikash Baruah

    2011-03-01

    Hydrolytic and solvolytic ring opening reactions of phthalic anhydride, pyromellitic dianhydride and 2,3-pyridine dicarboxylic anhydride in the presence of various transition metal salts with or without a ancillary ligands were studied. The reactions were found to be dependent on stoichiometry of ligand and types of anhydride used. In the case of pyromellitic dianhydride selective ring opening reaction by cobalt(II) ions gave 1,3-benzene dicarboxylate derivatives, whereas use of copper(II) ions gave 1,4-benzene dicarboxylate derivatives. Preference for methanolysis was seen in the case of copper (II) promoted reactions of pyromellitic dianhydride in the presence of 1:1 metal to 1,10-phenanthroline ratio.

  16. Crystal structure of 2,3-di-methyl-maleic anhydride: continuous chains of electrostatic attraction.

    Science.gov (United States)

    Wiscons, Ren A; Zeller, Matthias; Rowsell, Jesse L C

    2015-08-01

    In the crystal structure of 2,3-di-methyl-maleic anhydride, C6H6O3, the closest non-bonding inter-molecular distances, between the carbonyl C and O atoms of neighboring mol-ecules, were measured as 2.9054 (11) and 3.0509 (11) Å, which are well below the sum of the van der Waals radii for these atoms. These close contacts, as well as packing motifs similar to that of the title compound, were also found in the crystal structure of maleic anhydride itself and other 2,3-disubstituted maleic anhydrides. Computational modeling suggests that this close contact is caused by strong electrostatic inter-actions between the carbonyl C and O atoms.

  17. Solid—Liquid Equilibria of Several Binary and Ternary Systems Containing Meleic Anhydride

    Institute of Scientific and Technical Information of China (English)

    MAPeisheng; CHENMingming; 等

    2002-01-01

    Solid-liquid equilibria(SLE) of three binary systems and seven ternary systems containing maleic anhydride(MA) are measured by visual method. The experimental data are compared with the calculated ones with modified universal quasichemical functional group activity coefficient(UNIFAC) method in which the interaction parameters between groups come from two sources,dortmund data bank (DDB), if there′s any,and correlations based on our former presented experimental SLE data of twenty binary systems.New groups of MA,ACCOO group,COO group,>C=O group and cy-CH2 group are defined and the SLE data of maleic anhydride in isopropyl acetate in literature are cited in order to assess the new interaction parameters,correlated with Wilson equation and the λh equation.The modified UNIFAC method with these new regressed interaction parameters is also used to predict other three binary systems containing maleic anhydride.

  18. Hydrolysis and stability of thin pulsed plasma polymerised maleic anhydride coatings

    DEFF Research Database (Denmark)

    Drews, Joanna Maria; Launay, Héléne; Hansen, Charles M.;

    2008-01-01

    Abstract The stability of plasma polymerised layers has become important because of their widespread use. This study explored the hydrolysis and degradation stability of coatings of plasma polymerised maleic anhydride. Coatings made with different plasma parameters were exposed to aqueous media...... of different pH as a function of time. ATR-FTIR was used for structure analysis and a toluidine blue staining method allowed quantitative analysis of the hydrolysis of anhydride groups to acid groups. Coatings with constant thickness were obtained at different plasma powers and layers with varying thickness...

  19. CATALYSIS OF POLYSTYRENE N-HYDROXYL SULFONAMIDE FOR ESTERIFICATION OF BUTANOL WITH ACETIC ANHYDRIDE

    Institute of Scientific and Technical Information of China (English)

    LI Shufeng; LI Qian; YANG Xinlin; HUANG Wenqiang

    2004-01-01

    Polystyrene N-hydroxyl sulfonamide resin 1 was prepared and used to catalyze the esterification of n-butanol and acetic anhydride. The mechanism of catalytic esterification proved by IR spectra of the resins was found that O-H and N-H of the N-hydroxyl sulfonamide resin reacted with the acetic anhydride respectively to form the active intermediate polystyrene N,O-diacetyl sulfonamate which was cleaved by n-butanol to produce butyl acetate. The catalytic esterification by resin 1 was in good agreement with the kinetic model of "bi-bi-ping-pong" mechanism.

  20. Solvent-free esterification of poly(vinyl alcohol) and maleic anhydride through mechanochemical reaction

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A solid-state mechanochemical processing, that is, pan-milling, was used to conduct the esterification of poly(vinyl alcohol)(PVA) with maleic anhydride (MA) through stress-induced reaction. FTIR spectrum study indicated the presence of ester linkages and olefinic double bonds in maleic anhydride cross-linked PVA. Thermal properties of the cross-linked product were characterized by DSC. The results showed its glass transition temperature was 20 ℃ higher than the original linear PVA and the thermal stability was also improved.

  1. Synthesis and Characterization of a Novel Biomaterial:Maleic Anhydride-modified Poly(dl-lactic acid)

    Institute of Scientific and Technical Information of China (English)

    Yan Feng LUO; Yuan Liang WANG; Xu Feng NIU; Jun PAN; Liang Ping SHI

    2004-01-01

    A novel modified poly(dl-lactic acid) (PDLLA) was obtained by covalently grafting of maleic anhydride onto the backbone of PDLLA, attempting to improve PDLLA's hydrophilicity and cell affinity and to provide reactive groups for further chemical modification. FTIR, 13C NMR and DSC were used to characterize the maleic anhydride-modified PDLLA.

  2. Influence of the degree of hydrolysis of poly(styrene-alt-maleic anhydride) on miscibility with poly(vinyl acetate)

    NARCIS (Netherlands)

    Bosma, M.; Vorenkamp, E.J.; Brinke, G. ten; Challa, G.

    1988-01-01

    The influence of the hydrolysis of anhydride groups in poly(styrene-alt-maleic anhydride) (PSMA) on its miscibility with poly(vinyl acetate) (PVAc) is investigated. The cloudpoint curves of these blends are determined as a function of the degree of hydrolysis. The miscibility is shown to improve wit

  3. Curing efficiency of various types of light-curing units.

    Science.gov (United States)

    Rahiotis, Chris; Kakaboura, Afrodite; Loukidis, Michalis; Vougiouklakis, George

    2004-02-01

    This study compared monomer conversion (DC), the per cent linear polymerization shrinkage (%LS), the wall-to-wall contraction pattern (per cent of peripheral opening, %DM, and maximal marginal gap, MG) and depth of cure (DOC), of a hybrid resin composite (Spectrum TPH) exposed to different types of light-curing units and exposure modes (Virtuoso-PAC, Elipar TriLight-QTH, and FreeLight-LED). The QTH and LED units were used in two curing modes: the exponential ramp and the continuous output modes. Monomer conversion was investigated by micro Multiple Internal Reflection (MIR)-Fourier-transform infrared (FTIR) spectroscopy and %LS was measured by the deflective disc method. The wall-to-wall contraction method used a cylindrical cavity model in extracted human teeth. The per cent debonded margins relative to the cavity periphery (%DM) and the width of maximum gap (MG) was evaluated. The DOC was determined using Vickers microhardness measurements (200 g load, 20 s) at the top surface (H0), at 2 mm (H2) and at 4 mm (H4) depths, and the results expressed as H2/H0 and H4/H0 ratios. Significantly lower %DC and %LS values were provided by PAC and LED units. No differences were found in %DM among the curing units and PAC exhibited the highest MG. No significant differences were noted among light-curing groups in terms of H2/H0 microhardness values. The QTH, operated in exponential mode, resulted in the highest H4/H0 value. The exponential mode of the QTH demonstrated superior performance for the total of the characteristics evaluated.

  4. 双环笼状取代倍半硅氧烷/环氧树脂的固化机理及其性能%Curing Behavior and Properties of Epoxy Resin in the Presence of Silsesquioxane——Based Curing Agent

    Institute of Scientific and Technical Information of China (English)

    张利利; 刘安华; 曾幸荣

    2008-01-01

    The curing system of diglycidyl ether of bisphenol A (DGEBA) with octa (1-oxo-1-phospha-2, 6, 7-trioxabicyclo [2.2.2]-4-methylene) silsesquioxane (OSSQ) was studied by the differential scanning calorimetry (DSC). The activation energy (E.) and the pre-exponential factor (A0) of curing reaction, determined according to the Kissinger's method, were found to be 52.6kJ·mol-1 and 1.44 ×103 min-1. The thermal stability and flame retardancy of DGEBA/OSSQ were evaluated by thermogravimetry analysis (TGA) and Limiting Oxygen Index (LOI). Synergistic effect between phosphorus and silicon combined with the rigid structure of silsesquioxane resulted in good flame retardaney and thermal stability, the charred residue of DGEBA/OSSQ kept as high as 24.5% at the 700℃, the value of LOI was 25. The glass transition temperature (Tg) and storage modulus (E') were measured by dynamical mechanical analysis (DMA). DGEBA/ OSSQ possessed good low temperature toughness, the impact strength was 3.63kJ·m-2 and the Rockwell hardness was 76 at 14℃. Results demonstrate that OSSQ serviced as a multifunctional curing agent of epoxy resin with the properties of toughening and flame retarding.%利用DSC法研究了双环笼状取代倍半硅氧烷/环氧树脂的固化过程,根据Kissinger'S方程计算出固化反应表观活化能和表观指前因子分别为52.6kJ·mol-1和1.44×103min-1.利用热重分析和氧指数法研究了材料的热稳定和阻燃性能,磷硅两元素的协同阻燃效应及笼状骨架的共同作用提高了材料的热稳定性和阻燃性,在700℃时成炭量高达24.5%,氧指数为25.通过动态热机械分析仪表征了材料的玻璃化温度和储能模量.双环笼状取代倍半硅氧烷固化环氧树脂具有较好的低温韧性,在14℃时冲击韧度为3.63kJ·m-2,洛氏硬度为76.结果表明双环笼状取代倍半硅氧烷是一种兼具增韧和阻燃性能的多功能环氧树脂固化剂.

  5. Breather cloth for vacuum curing

    Science.gov (United States)

    Reed, M. W.

    1979-01-01

    Finely-woven nylon cloth that has been treated with Teflon improves vacuum adhesive bonding of coatings to substrates. Cloth is placed over coating; entire assembly, including substrate, coating, and cloth, is placed in plastic vacuum bag for curing. Cloth allows coating to "breathe" when bag is evacuated. Applications include bonding film coatings to solar concentrators and collectors.

  6. SELECTIVE HYDROGENATION OF ANHYDRIDES TO LACTONES UNDER SUPERCRITICAL CARBON DIOXIDE MEDIUM

    Science.gov (United States)

    Selective Hydrogenation of Anhydrides to Lactones Under Supercritical Carbon Dioxide MediumEndalkachew Sahle-Demessie Unnikrishnan R PillaiU.S. EPA , 26 W. Martin Luther King Dr. Cincinnati, OH 45268 Phone: 513-569-7739Fax: 513-569-7677Abstract:Hydrogenat...

  7. Molecular characterization of trimellitic anhydride-induced respiratory allergy in Brown Norway rats

    NARCIS (Netherlands)

    Kuper, C.F.; Heijne, W.H.; Dansen, M.; Verhoeckx, K.C.; Boorsma, A.; Radonjic, M.; Bruijntjes, J.; Stierum, R.; Muijser, H.; Arts, J.H.

    2008-01-01

    To contribute to the hazard identification of low molecular weight (LMW) respiratory allergens, respiratory allergy induced by trimellitic anhydride (TMA) was characterized by whole genome analysis of lung tissue and blood proteomics in Brown Norway rats. Dermal sensitization (50% and 25% w/v) with

  8. THE GRAFTING OF MALEIC-ANHYDRIDE ON HIGH-DENSITY POLYETHYLENE IN AN EXTRUDER

    NARCIS (Netherlands)

    GANZEVELD, KJ; JANSSEN, LPBM

    1992-01-01

    The grafting of maleic anhydride (MAH) on high density polyethylene in a counter-rotating twin screw extruder has been studied. As the reaction kinetics appear to be affected by mass transfer, good micro mixing in the extruder is important. Due to the competing mechanisms of increasing mixing and de

  9. Maleic anhydride based copolymer dispersions for surface modification of polar substrates

    NARCIS (Netherlands)

    Gunbas, I.D.; Wouters, M.E.L.; Hendrix, M.M.R.M.; Benthem, R.A.T.M. van; Koning, C.E.; Noordover, B.A.J.

    2012-01-01

    In this article, we report the modification of poly(styrene-alt-maleic anhydride) (PSMA) with monofunctional amine-terminated poly(dimethyl siloxane) (PDMS-NH2) by thermal imidization, followed by the preparation and characterization of a surfactant-free artificial latex thereof and application of t

  10. Triflic Anhydride-Mediated Beckmann Rearrangement Reaction of Β-Oximyl Amides: Access to 5-Iminooxazolines

    Indian Academy of Sciences (India)

    MANGFEI YU; QIAN ZHANG; JIA WANG; PENG HUANG; PENGFEI YAN; RUI ZHANG; DEWEN DONG

    2016-06-01

    Facile and efficient synthesis of 5-iminooxazolines fromΑ, Α-disubstituted Β-oximyl amidesmediated by triflic anhydride $(Tf_{2}O)$ in the presence of 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU) indichloromethane at room temperature is developed, and a mechanism involving tandem Beckmann rearrangementand intramolecular cyclization reaction is proposed.

  11. Aliphatic amine cured PDMS–epoxy interpenetrating network system for high performance engineering applications—Development and characterization

    Indian Academy of Sciences (India)

    T V Thanikai Velan; I Mohammed Bilal

    2000-10-01

    A siliconized epoxy interpenetrating network (IPN) was synthesized from commercially available DGEBA epoxy resin GY250 (Ciba-Geigy, epoxy equivalent = 182–192, viscosity = 9000–12000 cP) and hydroxyl terminated polydimethylsiloxane (PDMS). PDMS and GY250 were thoroughly mixed at 30°C to get the prepolymer. Stoichiometric amounts of PDMS–epoxy prepolymer, -aminopropyltriethoxysilane, aliphatic amine curing agent (HY951), and dibutyltindilaurate catalyst, were thoroughly mixed and cast in a mould after evacuating the entrapped air. The cured material was then taken out and post cured at 70°C for 10 h. IPN was characterized by FTIR spectroscopy, SEM, DSC, TGA and viscosity measurements. Incorporation of PDMS in the epoxy matrix increased the viscosity and lowered the exotherm and pot-life. PDMS in IPN increased , heat-distortion temperature and reduced the percentage weight loss with increase in temperature. Incorporation of PDMS drastically reduced the tensile and flexural strengths and hardness. By reducing the tensile and flexural modulus, the siloxane moiety effectively reduced the internal stress of IPN thereby improving its impact strength and percentage elongation. PDMS increased the electric potential gradient of IPN to withstand without breakdown. An increase in the tracking index and arc resistance of IPN were observed, because of the presence of Si–O–Si, which minimized the possibility of forming carbonized path. Volume and surface resistivities of IPN also increased with the incorporation of PDMS. The siliconized epoxy IPN, with better impact and thermal resistance, may be used in automobile and aerospace applications to withstand high temperature, and mechanical stress. The PDMS–epoxy IPN may be used for encapsulation, high temperature and high voltage application due to their low shrinkage and lesser internal stress. With the improved electrical characteristics, IPN may be used for high performance electrical insulation, insulator housings

  12. Microwave synthesis and thermal properties of polyacrylate derivatives containing itaconic anhydride moieties

    Directory of Open Access Journals (Sweden)

    Osman Sameh M

    2012-08-01

    Full Text Available Abstract Background Microwave irradiation as an alternative heat source is now a well-known method in synthetic chemistry. Microwave heating has emerged as a powerful technique to promote a variety of chemical reactions, offering reduced pollution, low cost and offer high yields together with simplicity in processing and handling. On the other hand, copolymers containing both hydrophilic and hydrophobic segments are drawing considerable attention because of their possible use in biological systems. Various copolymer compositions can produce a very large number of different arrangements, producing materials of varying chemical and physical properties. Thus, the hydrophilicity of copolymers can be modified by changing the amount of incorporated itaconic anhydride. Results A series of methyl methacrylate (MMA and acrylamide (AA copolymers containing itaconic anhydride (ITA were synthesized by microwave irradiation employing a multimode reactor (Synthos 3000 Aton Paar, GmbH, 1400 W maximum magnetron as well as conventional method. The thermal properties of the copolymers were evaluated by different techniques. Structure-thermal property correlation based on changing the itaconic anhydride ratio was demonstrated. Results revealed that the incorporation of itaconic anhydride into the polymeric backbone of all series affect the thermal stability of copolymers. In addition, the use of the microwave method offers high molecular weight copolymers which lead eventually to an increase in thermal stability. Conclusions Microwave irradiation method showed advantages for the produced copolymers compared to that prepared by conventional method, where it can offer a copolymer in short time, high yield, more pure compounds and more thermally stable copolymers, rather than conventional method. Also, microwave irradiation method gives higher molecular weight due to prevention of the chain transfer. Moreover, as the itaconic anhydride content increases the thermal

  13. Rapid Development of the Radiation Curing Sector

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Radiation curing is an advanced material surface treatment technology using ultraviolet (UV) radiation and electronic beams (EB). With the greater attention paid to environ mentel protection in recent years ,radiation curing has developed rapidly.

  14. Accelerated Cure Project for Multiple Sclerosis

    Science.gov (United States)

    ... main content Accelerating research toward a cure for multiple sclerosis Home Contact Us Search form Search Connect Volunteer ... is to accelerate efforts toward a cure for multiple sclerosis by rapidly advancing research that determines its causes ...

  15. Envelhecimento físico de sistemas DGEBA/DDM investigado por análise térmica (DSC/DMA

    Directory of Open Access Journals (Sweden)

    Riegel Izabel C.

    1999-01-01

    Full Text Available Neste trabalho, estudou-se o efeito do envelhecimento físico nas propriedades térmicas e mecânicas em sistemas diglicidil éter do bisfenol-A (DGEBA/diaminodifenilmetano (DDM, em função do grau de conversão, induzido pela cura e do tempo de envelhecimento. A cura isotérmica foi realizada em uma etapa a 115°C por diversos tempos e o envelhecimento foi conduzido a 100°C por períodos de 240 a 4320 min. Considerando que o envelhecimento físico acarreta variações estruturais as quais afetam tanto o desempenho mecânico quanto as propriedades termodinâmicas do material, as técnicas de DSC e DMA são complementares. Através de Calorimetria Exploratória Diferencial (DSC, observou-se que o envelhecimento físico está associado ao pico endotérmico que ocorre na região da transição vítrea e que a entalpia de relaxação, calculada a partir da área deste pico, aumenta gradualmente com o tempo de envelhecimento. Os resultados obtidos por Análise Dinâmico-Mecânica (DMA mostraram um aumento do módulo elástico E' com o tempo de envelhecimento. As velocidades de envelhecimento foram obtidas a partir da temperatura do pico endotérmico, a partir do módulo elástico E' e a partir da temperatura de transição vítrea e resultaram tanto menores quanto maior o grau de conversão da matriz. Os resultados salientam a importância da seleção adequada das condições de cura para que se possam obter as melhores propriedades destes materiais. A importância dos fenômenos observados é considerada, tendo-se em vista a grande utilização e aplicabilidade das resinas epóxi.

  16. Techniques for internal water curing of concrete

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Pietro, Lura

    2003-01-01

    This paper gives an overview of different techniques for incorporation of internal curing water in concrete. Internal curing can be used to mitigate self-desiccation and self-desiccation shrinkage. Some concretes may need 50 kg/m3 of internal curing water for this purpose. The price of the internal...

  17. From HCV To HBV Cure.

    Science.gov (United States)

    Schinazi, Raymond F; Asselah, Tarik

    2017-01-01

    Approximately 170 million people are chronically infected with HCV and 350 million are chronically infected with HBV worldwide. It is estimated that more than one million patients die from complications related to chronic viral hepatitis, mainly HCC which is one of the most frequent cancers in many countries, especially Africa, the Middle East and Asia. HCV drug development has been impressive, and this revolution led to several direct-acting antiviral agents achieving an HCV cure after only 6-12 weeks. This progress could theorically lead to HCV global elimination making HCV and its consequences a rarity. HBV research and development programs can learn from the HCV experience, to achieve an HBV functional or sterilizing cure. This review will summarize key steps which have been realized for an HCV cure, and discuss the next steps to achieve for an HCV elimination. And also, how this HCV revolution has inspired scientists and clinicians to achieve the same for HBV.

  18. Freud's psychoanalysis: a moral cure.

    Science.gov (United States)

    Eriksson, Johan

    2014-08-01

    That psychoanalytical treatment in its classical Freudian sense is primarily a moral or ethical cure is not a very controversial claim. However, it is far from obvious how we are to understand precisely the moral character of psychoanalysis. It has frequently been proposed that this designation is valid because psychoanalysis strives neither to cure psychological symptoms pharmaceutically, nor to superficially modify the behaviour of the analysand, but to lead the analysand through an interpretive process during which he gradually gains knowledge of the unconscious motives that determine his behaviour, a process that might ideally liberate him to obtain, in relation to his inner desires, the status of a moral agent. There resides something appealing in these claims. But it is the author's belief that there is an even deeper moral dimension applying to psychoanalytical theory and praxis. Freudian psychoanalysis is a moral cure due to its way of thematizing psychological suffering as moral suffering. And this means that the moral subject - the being that can experience moral suffering - is not primarily something that the psychoanalytical treatment strives to realize, but rather the presupposition for the way in which psychoanalysis theorizes psychological problems as such.

  19. Composite cure monitoring with Bragg grating sensors

    Science.gov (United States)

    Slattery, Kerry T.; Corona-Bittick, Kelli; Dorr, Donald J.

    1998-03-01

    Residual stress is induced in fiber composite materials during the cure process because the thermal expansion coefficient of the fiber is generally much lower than that of the polymer matrix. The two materials are 'locked' together at the cure temperature. Then, as they cool, the matrix attempts to contract more than the fiber leading to tension in the matrix and compression in the fiber. This can lead to the formation of microcracks parallel to the fibers in thick composite piles or yarns. The magnitude of residual stress can be reduced by modifying the cure cycle; however, optimizing the cure cycle requires a complete understanding of the state of cure throughout the composite. This is a complex problem -- especially in thick composites. Pilot studies have been performed placing Bragg gratin sensors in glass fabric preforms and monitoring the response of the grating during resin infusion and cure. The typical response shows the initial thermal expansion of the Bragg grating, a rapid contraction of the grating as the resin gels, slower contraction during cure, and thermal contraction at the composite thermal expansion coefficient during cool down. This data is then sued with micromechanical models of the fiber/matrix interaction during cure to establish material parameters for cure simulation. Once verified, these cure simulation methods will be used to optimize tooling design and cure cycles in composite components.

  20. A new process for the valorisation of a bio-alcohol. The oxidehydration of 1-butanol into maleic anhydride

    Energy Technology Data Exchange (ETDEWEB)

    Caldarelli, A.; Cavani, F.; Garone, O.; Pavarelli, G. [Bologna Univ. (Italy). Dipt. di Chimica Industriale e dei Materiali; Bologna Univ. (Italy). CIRCC, Research Unit; Dubois, J.L. [ARKEMA, Colombes (France); Mitsova, I.; Simeonova, L. [JSC, Russe (Bulgaria). Orgachim

    2012-07-01

    This paper deals with a study on the gas-phase transformation of 1-butanol into maleic anhydride, using different types of catalysts. Indeed, catalytic acid properties are needed to dehydrate 1-butanol into 1-butene, whereas redox-type properties are required for the oxidation of the olefin into maleic anhydride. The two types of active sites can be combined in bifunctional systems, showing both acid and redox-type properties. We found that vanadyl pyrophosphate catalyzes the one-pot reaction, giving a maximum selectivity to maleic anhydride of 28%. In fact, various side reactions contributed to the formation of by-products, eg, 1-butanol (oxidative) dehydrogenation into butyraldehyde, formation of light carboxylic acids and carbon oxides, and condensation of unsaturated C{sub 4} intermediates (butenes and butadiene) with the formed maleic anhydride to yield heavier compounds. (orig.)

  1. Ruthenium-catalyzed decarbonylative addition reaction of anhydrides with alkynes: a facile synthesis of isocoumarins and α-pyrones.

    Science.gov (United States)

    Prakash, Rashmi; Shekarrao, Kommuri; Gogoi, Sanjib; Boruah, Romesh C

    2015-06-21

    A novel ruthenium catalyzed straightforward and efficient synthesis of isocoumarin and α-pyrone derivatives has been accomplished by the decarbonylative addition reaction of anhydrides with alkynes under thermal conditions.

  2. Preparation and characterization of poly(styrene/maleic anhydride)/kaolin nanocomposites

    Institute of Scientific and Technical Information of China (English)

    LIU Xuening; ZHANG Hongtao; YANG Zhizhong; HA Chengyong

    2005-01-01

    The direct exfoliation of in situ intercalative copolymerized styrene/maleic anhydride charge-transfercomplex (PSMA) into the inter lamellar spaces of modified kaolin (Kao-DMSO), which was intercalated and surface modified by dimethyl sulfoxide (DMSO), was reported. The nano structure of the composites was investigated by wide-angle X-ray diffraction (XRD) and transmission electron microscopy (TEM). The interaction between kaolin surface and PSMA chain was conformed by FTIR analysis. The XRD results showed that the intercalated polystyrene-maleic anhydride units were arranged in the flattened monolayer arrangements, and the 001 diffraction peak of the original kaolin disappeared. The TEM image showed that the kaolin was exfoliated into nanometer size and dispersed in the polymer matrix. Additionally the thermal stability of the nanocomposites was studied by thermo-gravimetric analysis (TGA), and the resulting thermogram indicated that the thermal stability of the nanocomposites was significantly increased.

  3. Electron paramagnetic resonance and FT-IR spectroscopic studies of glycine anhydride and betaine hydrochloride

    Science.gov (United States)

    Halim Başkan, M.; Kartal, Zeki; Aydın, Murat

    2015-12-01

    Gamma irradiated powders of glycine anhydride and betaine hydrochloride have been investigated at room temperature by electron paramagnetic resonance (EPR). In these compounds, the observed paramagnetic species were attributed to the R1 and R2 radicals, respectively. It was determined that the free electron interacted with environmental protons and 14N nucleus in both radicals. The EPR spectra of gamma irradiated powder samples remained unchanged at room temperature for two weeks after irradiation. Also, the Fourier Transform Infrared (FT-IR), FT-Raman and thermal analyses of both compounds were investigated. The functional groups in the molecular structures of glycine anhydride and betaine hydrochloride were identified by vibrational spectroscopies (FT-IR and FT-Raman).

  4. Physicochemical Characterization and the Comparison of Chitin and Chitin Modified with Maleic Anhydride

    Directory of Open Access Journals (Sweden)

    İlhan Uzun

    2015-06-01

    Full Text Available Firstly, chitin was modified via ring-opening reaction with maleic anhydride in lithium chloride/N,N-dimethylacetamide. Then, both chitin and chitin modified with maleic anhydride (CMA were characterized by Fourier transform infrared (FTIR spectroscopy, X-ray diffraction (XRD method, ultraviolet-visible (UV-Vis spectroscopy, and scanning electron microscopy (SEM. Thermogravimetric analysis (TGA was performed to investigate the thermal stability of chitin and CMA. TGA results showed that chitin is thermally more stable than CMA. In addition, the electrical conductivity of chitin and CMA was also measured. Electrical conductivity measurement results showed that the electrical conductivity of CMA (4.3x10-4 S cm-1 is more than that of chitin (6.5x10-6 S cm-1.

  5. Wheat Gluten Blends with Maleic Anhydride-Functionalized Polyacrylate Cross-Linkers for Improved Properties.

    Science.gov (United States)

    Diao, Cheng; Xia, Hongwei; Parnas, Richard S

    2015-10-14

    A family of polyacrylate-based cross-linkers was synthesized to maximize the toughness of high Tg, high modulus wheat gluten blends in the glassy state. Mechanical testing and damping measurements were conducted to provide an example where the work of fracture and strength of the blend substantially exceeds polystyrene while maintaining flexure stiffness in excess of 3 GPa. The new rubbery cross-linkers, polymethyl acrylate-co-maleic anhydride and polyethyl acrylate-co-maleic anhydride, improve WG mechanical properties and reduce water absorption simultaneously. MDSC, FTIR, HPLC, and NMR data confirmed the cross-linking reaction with wheat gluten. Flexural, DMA, and water absorption testing were carried out to characterize the property improvements. DMA was conducted to investigate the relationship between energy damping and mechanical property improvement. If the cross-linker damping temperature is close to the testing temperature, the entire sample exhibits high damping, toughness, and strength.

  6. Preparation and Physical Properties of Chitosan Benzoic Acid Derivatives Using a Phosphoryl Mixed Anhydride System

    Directory of Open Access Journals (Sweden)

    Kyu Yun Chai

    2012-02-01

    Full Text Available Direct benzoylation of the two hydroxyl groups on chitosan was achieved using a phosphoryl mixed anhydride system, derived from trifluoroacetic anhydride (TFAA, benzoic acids (BAs, and phosphoric acid (PA. The reaction is operated as a one pot process under mild conditions that does not require neither an inert atmosphere nor dry solvents. The structures of the synthesized compounds were confirmed by NMR and IR spectroscopy. Solubility tests on the products revealed that they were soluble in organic solvents such as N,N-dimethylformamide (DMF, dimethylsulfoxide (DMSO, and acetone. In the meantime, a morphological study by scanning electron microscopy (SEM evidently indicated that the chitosan benzoates underwent significant structural changes after the benzoylation.

  7. Graft Copolymers of Maleic Anhydride and Its Isostructural Analogues: High Performance Engineering Materials

    CERN Document Server

    Rzayev, Zakir M O

    2011-01-01

    This review summarizes the main advances published over the last 15 years outlining the different methods of grafting, including reactive extruder systems, surface modification, grafting and graft copolymerization of synthetic and natural polymers with maleic anhydride and its isostructural analogues such as maleimides and maleates, and anhydrides, esters and imides of citraconic and itaconic acids, derivatives of fumaric acid, etc. Special attention is spared to the grafting of conventional and non-conventional synthetic and natural polymers, including biodegradable polymers, mechanism of grafting and graft copolymerization, in situ grafting reactions in melt by reactive extrusion systems, in solutions and solid state (photo- and plasma-induced graftings), and H-bonding effect in the reactive blend processing. The structural phenomena, unique properties and application areas of these copolymers and their various modifications and composites as high performance engineering materials have been also described.

  8. Comparison of curing behaviors and mechanical properties of epoxy resin system in different curing approaches%不同固化方式下环氧树脂体系固化行为及力学性能研究

    Institute of Scientific and Technical Information of China (English)

    孙涛; 常新龙; 赖建伟; 方鹏亚

    2012-01-01

    分别采用热固化、微波固化及微波和热组合固化3种方式对双酚A环氧树脂/4,4'二氨基二苯甲烷(DDM)体系进行了固化试验研究,用红外光谱法(FT-IR)、差示扫描量热仪(DSC)、扫描电镜(SEM)等分析其固化行为及微观形态表征,对固化试样进行了力学性能测试.研究结果表明,微波固化能显著提高体系的固化反应速率,缩短凝胶化时间,微波固化及微波和热组合固化达到完全的时间仅分别为0.9h和1.5h,微波固化产物具有比热固化产物高的玻璃化转变温度(Tg);组合固化试样的拉伸强度能达到热固化试样的95%以上,但微波固化试样拉伸强度仅为热固化试样的80%,扫描电镜分析表明微波固化产物在微观形态上与热固化及组合固化产物有较大差别.%Curing of the epoxy resin system of di-glycidyl ether of bisphenol-A( DGEBA) with curing agent of 4,4' diamino-di-phenyl-methane(DDM) was studied using three methods,i. e. microwave, conventional oven and combined method. Curing behaviors and mechanical properties of epoxy resin system were investigated through a number of techniques including differential scanning calorimetry (DSC) , fourier transform infrared spectrometer (FTIR) and scanning electron microscope (SEM). Results show that polymerization reaction occurs at a faster rate during microwave heating than that in conventional oven heating thus reduces the gelation and cure time, the completely cure time of the microwave and the combined method is 0.9 h and 1.5 h respectively. Analysis of DSC reveals higher glass transition temperature( Tg) in microwave processing compared with conventional oven heating. The tensile strength of specimens cured by combined method is similar to that of conventional thermal, while microwave-cured specimens owns lower mechanical properties. Finally, scanning electron microscope was used to analyze the morphology of cured specimens and it is found that the microstructure

  9. Perylene anhydride fused porphyrins as near-infrared sensitizers for dye-sensitized solar cells

    KAUST Repository

    Jiao, Chongjun

    2011-07-15

    Two perylene anhydride fused porphyrins 1 and 2 have been synthesized and employed successfully in dye-sensitized solar cells (DSCs). Both compounds showed broad incident monochromatic photon-to-current conversion efficiency spectra covering the entire visible spectral region and even extending into the near-infrared (NIR) region up to 1000 nm, which is impressive for ruthenium-free dyes in DSCs. © 2011 American Chemical Society.

  10. Dodecenylsuccinic Anhydride Derivatives of Gum Karaya (Sterculia urens): Preparation, Characterization, and Their Antibacterial Properties

    OpenAIRE

    Padil, V.V.T.; Senan, Chandra; Cernik, M

    2015-01-01

    Esterifications of the tree-based gum, gum karaya (GK), using dodecenylsuccinic anhydride (DDSA) were carried out in aqueous solutions. GK was deacetylated using alkali treatment to obtain deacetylated gum karaya (DGK). The DGK and its DDSA derivative were characterized using gel permeation chromatography/multiangle laser light scattering (GPC/MALLS), attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), proton nuclear magnetic re...

  11. Synthesis and Characterization of Organic Impurities in Bortezomib Anhydride Produced by a Convergent Technology

    Science.gov (United States)

    Ivanov, Andrey S.; Shishkov, Sergey V.; Zhalnina, Anna A.

    2012-01-01

    A profile of impurities in bortezomib anhydride, produced by a recently developed convergent technology, has been characterized. HPLC-MS analysis of the drug essence revealed three impurities: an epimer of bortezomib, resulting from partial racemization of l-phenylalanine’s stereogenic center during the chemical synthesis, and two epimeric products of oxidative degradation of bortezomib, in which boron is replaced by the OH group. The impurities were obtained by chemical synthesis and characterized by physical methods. PMID:22396904

  12. Study on oil absorbency of succinic anhydride modified banana cellulose in ionic liquid.

    Science.gov (United States)

    Shang, Wenting; Sheng, Zhanwu; Shen, Yixiao; Ai, Binling; Zheng, Lili; Yang, Jingsong; Xu, Zhimin

    2016-05-05

    Banana cellulose contained number of hydrophilic hydroxyl groups which were succinylated to be hydrophobic groups with high oil affinity. Succinic anhydride was used to modify banana cellulose in 1-allyl-3-methylimidazolium chloride ionic liquid in this study. The modified banana cellulose had a high oil absorption capacity. The effects of reaction time, temperature, and molar ratio of succinic anhydride to anhydroglucose on the degree of substitution of modified banana cellulose were evaluated. The optimal reaction condition was at a ratio of succinic anhydride and anhydroglucose 6:1 (m:m), reaction time 60min and temperature 90°C. The maximum degree of acylation reaction reached to 0.37. The characterization analysis of the modified banana cellulose was performed using X-ray diffractometer, Fourier transform infrared spectrometer, scanning electron microscopy and thermogravimetry. The oil absorption capacity and kinetics of the modified banana cellulose were evaluated at the modified cellulose dose (0.025-0.3g), initial oil amount (5-30g), and temperature (15-35°C) conditions. The maximum oil absorption capacity was 32.12g/g at the condition of the cellulose dose (0.05g), initial oil amount (25g) and temperature (15°C). The kinetics of oil absorption of the cellulose followed a pseudo-second-order model. The results of this study demonstrated that the modified banana cellulose could be used as an efficient bio-sorbent for oil adsorption.

  13. Cure-A-Phobia感

    Institute of Scientific and Technical Information of China (English)

    黄乔

    2015-01-01

    爵士乐源于二十世纪的非洲黑人音乐,被公认为欧洲现代流行音乐的开端,随着二十一世纪多元化文化的不断呈现,爵士乐在我国也愈来愈受到关注.特别是在各艺术类院校,相关爵士乐教学及演出活动也越来越多.本文在此将对瑞典爵士乐队Cure-A-Phobia的一场音乐会略抒己见.

  14. 超支化聚苯醚对双酚A型环氧树脂的低介电改性%Low dielectric constant modification of bisphenol A diglycidyl ether with hyperbranched poly (phenylene oxide)

    Institute of Scientific and Technical Information of China (English)

    吕健勇; 孟焱; 何立凡; 邱藤; 李效玉; 王海侨

    2013-01-01

    自制了一种反应型端环氧基超支化聚苯醚(EHPPO),将其添加到双酚A型环氧树脂中进行改性并用酸酐固化剂固化,表征了固化样品的热性能、力学性能和介电性能.此外还使用分子主链结构相同、端基为非反应型苄基的超支化聚苯醚(CHPPO)进行了对比改性研究.结果表明,两种不同的改性剂对双酚A型环氧树脂的改性效果各有优势,其中,使用EHPPO改性得到的环氧树脂具有更加优异的热性能和拉伸强度,而由CHPPO改性的环氧树脂介电常数相对更低.%A reactive epoxidized hyperbranched poly(phenylene oxide) (EHPPO) was added to the diglycidyl ether of bisphenol A (DGEBA) to form a hybrid which was cured with methyl-5-norbornene-2,3-dicarboxylic anhydride (methyl nadic anhydride) in order to improve its thermal and dielectric properties.The thermal and dielectric properties of the cured hybrid were investigated.In addition,as a non-reactive modifier,benzyl-capped hyperbranched poly (phenylene oxide) (CHPPO) was prepared and added to DGEBA for comparison.The results showed that addition of EHPPO and CHPPO can improve both thermal and dielectric properties of DGEBA.Hybrids with EHPPO have much higher glass transition temperature and better thermal stability than those with CHPPO,whereas,DGEBA/CHPPO hybrids have lower dielectric constants than DGEBA/EHPPO hybrids.

  15. Interfacial Properties of Electron Beam Cured Composites

    Energy Technology Data Exchange (ETDEWEB)

    Eberle, C.C.

    1999-12-30

    The objectives of the CRADA are to: Confirm that fiber-resin adhesion is responsible for the observed poor shear properties; Determine the mechanism(s) responsible for poor adhesion between carbon fibers and epoxy resins after e-beam curing; Develop and evaluate resin systems and fiber treatments to improve the properties of e-beam cured, carbon-fiber-reinforced composites; and Develop refined methods for processing e-beam cured, carbon-fiber-reinforced composites.

  16. Microwave Cure of Phenol-Formaldehyde Adhesive

    OpenAIRE

    高谷, 政広; 田平, 英敏; 岡本, 忠

    2006-01-01

    [Synopsis] Phenol-formaldehyde resin has been used as a versatile material for adhesives and coatings of a wide range of adherends because of its excellent performance in water- resistance, strength against abrasion, and so on. However, it has a drawback of slow rate of cure and relevant emission of formaldehyde gas after bonding. We studied the curing performance under irradiation of microwave for the purpose of looking for a way of accelerating the cure rate of phenol formaldehyde resin. Th...

  17. Electron Beam Curing of Advanced Composites

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The fundamental concept of electron beam method and the application in cure of composites are elaborated in this paper. The components of electron beam curing system are introduced. The mechanisms of interaction between electron beam and polymer matrix composites are presented. Recent studies reported including work of authors themselves on electron beam curing of composites are also discussed. Moreover, the authors believe that it is necessary to do the basic research about understanding how electron beam affects cured network and the mechanical/physical properties of the composites, for establishing a quantitative or semi-quantitative formulation.

  18. XPS depth profiling of derivatized amine and anhydride plasma polymers: Evidence of limitations of the derivatization approach

    Science.gov (United States)

    Manakhov, Anton; Michlíček, Miroslav; Felten, Alexandre; Pireaux, Jean-Jacques; Nečas, David; Zajíčková, Lenka

    2017-02-01

    The quantitative analysis of the chemistry at the surface of functional plasma polymers is highly important for the optimization of their deposition conditions and, therefore, for their subsequent applications. The chemical derivatization of amine and carboxyl-anhydride layers is a well-known technique already applied by many researchers, notwithstanding the known drawback of the derivatization procedures like side or uncomplete reactions that could lead to "unreliable" results. In this work, X-ray photoelectron spectroscopy (XPS) combined with depth profiling with argon clusters is applied for the first time to study derivatized amine and carboxyl-anhydride plasma polymer layers. It revealed an additional important parameter affecting the derivatization reliability, namely the permeation of the derivatizing molecule through the target analysed layer, i.e. the composite effect of the probe molecule size and the layer porosity. Amine-rich films prepared by RF low pressure plasma polymerization of cyclopropylamine were derivatized with trifluoromethyl benzaldehide (TFBA) and it was observed by that the XPS-determined NH2 concentration depth profile is rapidly decreasing over top ten nanometers of the layer. The anhydride-rich films prepared by atmospheric plasma co-polymerization of maleic anhydride and C2H2 have been reacted with, parafluoroaniline and trifluoroethyl amine. The decrease of the F signal in top surface layer of the anhydride films derivatized by the "large" parafluoroaniline was observed similarly as for the amine films but the derivatization with the smaller trifluoroethylamine (TFEA) led to a more homogenous depth profile. The data analysis suggests that the size of the derivatizing molecule is the main factor, showing that the very limited permeation of the TFBA molecule can lead to underestimated densities of primary amines if the XPS analysis is solely carried out at a low take-off angle. In contrast, TFEA is found to be an efficient

  19. Curing efficiency of three light emitting diode units at different curing profiles

    Directory of Open Access Journals (Sweden)

    Priyanka Verma

    2016-01-01

    Conclusions: Reduction of exposure time to 6 s with high-intensity curing light seemed to be clinically acceptable and should be recommended. Curing of metal brackets with single exposure from buccal side showed lower shear bond strength values.

  20. Prevention is better than cure

    CERN Multimedia

    Anaïs Schaeffer

    2012-01-01

    Throughout the year, members of the Safety Inspections Services section of HSE Unit devote themselves to ensuring the safety of all infrastructure and equipment that represent a specific hazard within the Organization. They regularly comb through all CERN's infrastructure to forestall any accidents and their potential impact, true to the adage that prevention is better than cure.   This site has a few (!) slight safety problems... Spot the mistakes! (Details of the game below.) Ensuring that an HV electrical installation is properly earthed, that a system under pressure has no weak points, that an item of lifting equipment can be used without risk, that safety valves operate at the right pressure threshold as well as checking that a heavy object that could inflict injury if it fell is not stored on top of a cupboard: such are the types of inspections performed by the Safety Inspection Service (DGS-SEE-SIS). "These checks reassure those in charge of equipment and infrastruct...

  1. Hepatitis C, stigma and cure.

    Science.gov (United States)

    Marinho, Rui Tato; Barreira, David Pires

    2013-10-28

    The infection with hepatitis C virus (HCV) is one of the most important global chronic viral infections worldwide. It is estimated to affect around 3% of the world population, about 170-200 million people. Great part of the infections are asymptomatic, the patient can be a chronic carrier for decades without knowing it. The most severe consequences of the chronic infection are liver cirrhosis and hepatocellular carcinoma, which appears in 20%-40% of the patients, leading to hepatic failure and death. The HCV was discovered 25 years ago in 1989, is a RNA virus and classified by the World Health Organization as an oncogenic one. Hepatocellular carcinoma is one of the most important cancers, the fifth worldwide in terms of mortality. It has been increasing in the Ocidental world, mainly due to chronic hepatitis C. Hepatitis C is not only a liver disease and a cause of cirrhosis, but also a mental, psychological, familiar, and social disease. The stigma that the infected person sometimes carries is tremendous having multiple consequences. The main cause is lack of adequate information, even in the health professionals setting. But, besides the "drama" of being infected, health professionals, family, society and the infected patients, must be aware of the chance of real cure and total and definitive elimination of the virus. The treatment for hepatitis C has begun in the last 80's with a percentage of cure of 6%. Step by step the efficacy of the therapy for hepatitis C is rapidly increasing and nowadays with the very new medications, the so called Direct Antiviral Agents-DAAs of new generation, is around 80%-90%.

  2. Curing Mechanism of Condensed Polynuclear Aromatic Resin and Thermal Stability of Cured Resin

    Institute of Scientific and Technical Information of China (English)

    Li Shibin; Sun Qiqian; Wang Yuwei; Wu Mingbo; Zhang Zailong

    2015-01-01

    In order to improve the thermal stability of condensed polynuclear aromatic (COPNA) resin synthesized from vacuum residue, 1,4-benzenedimethanol was added to cure COPNA resin. The curing mechanism was investigated by pro-ton nuclear magnetic resonance spectrometry, solid carbon-13 nuclear magnetic resonance spectrometry and Fourier trans-form infrared spectroscopy. Microstructures of the uncured and the cured COPNA resins were studied by scanning electron microscopy and X-ray diffractometry. The thermal stability of COPNA resins before and after curing was tested by thermo-gravimetric analysis. The element composition of the cured COPNA resin heated at different temperatures was analyzed by an element analyzer. The results showed that the uncured COPNA resin reacted with the cross-linking agent during the cur-ing process, and the curing mechanism was conifrmed to be the electrophilic substitution reaction. Compared with the un-cured COPNA resin, the cured COPNA resin had a smooth surface, well-ordered and streamlined sheet structure with more crystalline solids, better molecular arrangement and orientation. The weight loss process of the uncured and cured COPNA resins was divided into three stages. Carbon residue of the cured COPNA resin was 41.65%at 600℃, which was much higher than 25.02%of the uncured COPNA resin, which indicated that the cured COPNA resin had higher thermal stability.

  3. UV-Assisted 3D Printing of Glass and Carbon Fiber-Reinforced Dual-Cure Polymer Composites

    Directory of Open Access Journals (Sweden)

    Marta Invernizzi

    2016-07-01

    Full Text Available Glass (GFR and carbon fiber-reinforced (CFR dual-cure polymer composites fabricated by UV-assisted three-dimensional (UV-3D printing are presented. The resin material combines an acrylic-based photocurable resin with a low temperature (140 °C thermally-curable resin system based on bisphenol A diglycidyl ether as base component, an aliphatic anhydride (hexahydro-4-methylphthalic anhydride as hardener and (2,4,6,-tris(dimethylaminomethylphenol as catalyst. A thorough rheological characterization of these formulations allowed us to define their 3D printability window. UV-3D printed macrostructures were successfully demonstrated, giving a clear indication of their potential use in real-life structural applications. Differential scanning calorimetry and dynamic mechanical analysis highlighted the good thermal stability and mechanical properties of the printed parts. In addition, uniaxial tensile tests were used to assess the fiber reinforcing effect on the UV-3D printed objects. Finally, an initial study was conducted on the use of a sizing treatment on carbon fibers to improve the fiber/matrix interfacial adhesion, giving preliminary indications on the potential of this approach to improve the mechanical properties of the 3D printed CFR components.

  4. Chemical and structural characterisation of DGEBA-based epoxies by time of flight secondary ion mass spectrometry (ToF-SIMS) as a preliminary to polymer interphase characterisation.

    Science.gov (United States)

    Passlack, Sven; Brodyanski, Alexander; Bock, Wolfgang; Kopnarski, Michael; Presser, Melanie; Geiss, Paul Ludwig; Possart, Gunnar; Steinmann, Paul

    2009-04-01

    Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has become a powerful tool in the field of surface analysis since it provides information about the top few monolayers of a sample, i.e. on the chemical composition of the sample surface. Thus, the general question arises whether a surface-sensitive technique like ToF-SIMS would be appropriate to detect systematic chemical and/or structural changes in organic bulk polymers caused by varying a chemical content of the initial components or by tracking, e.g. curing processes in such materials. It is shown that careful sample preparation and the use of multivariate methods permit the quantitative acquisition of chemical and structural information about bulk polymers from the secondary ion signals. The hardener concentration and a cross-linking coefficient in diglycidyl ether of bisphenol A based epoxies were determined by ToF-SIMS measurements on samples with different resin to hardener ratio and varying curing time. In future work, we will use the developed method to investigate the local composition of adhesively bonded joints. In particular, the mapping of the chemical and structural properties in the so-called interphase will then be of interest.

  5. Performance of CTBN(carboxyl-terminated poly (butadiene-co-acrylonitrile))-EP(diglycidyl ether of bisphenol-A(DGEBA)) Prepolymers and CTBN-EP/polyetheramine (PEA) System

    Institute of Scientific and Technical Information of China (English)

    SHI Minxian; HUANG Zhixiong; LI Yaming; YANG Guorui

    2009-01-01

    CTBN-EP prepolymers were synthesized from CTBN and epoxy resin under the catalysis of HTMAB.FTIR analyses indicate the formation of ester group between the carboxyl group of CTBN and the oxirane group of epoxy resin.The viscosity of modified prepolymer increases with CTBN content increasing,but the epoxy value of the prepolymer decreases greatly.DSC analyses verify that CTBN affects the curing process of CTBN-EP/PEA system.Mechanical testing presents the improved toughness of CTBN-EP/PEA curings for the decrease of tensile strength,flexural strength and compressive strength,and increase of impact strength and elongation-at-break with the CTBN content increasing.SEM micrographs show the rubber phase with many holes in diameter about 0.5-1.5μm is formed when CTBN content is lower than 10 phr.However,the pattern of SEM graph shows some stalactite-like strips when CTBN content is higher than 15 phr.Furthermore,the SEM image of 25 phr CTBN sample forms a kind of co-continuous structure.

  6. 7 CFR 29.6010 - Cured.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Cured. 29.6010 Section 29.6010 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6010 Cured. Tobacco dried of its sap by either natural or...

  7. Dental resin cure monitoring by inherent fluorescence

    Science.gov (United States)

    Li, Qun; Zhou, Jack X.; Li, Qingxiong; Wang, Sean X.

    2008-02-01

    It is demonstrated that the inherent fluorescence of a dental composite resin can be utilized to monitor the curing status, i.e. degree of conversion of the resin. The method does not require any sample preparation and is potentially very fast for real time cure monitoring. The method is verified by Raman spectroscopy analysis.

  8. Quantification of free sphingosine in cultured cells by acylation with radioactive acetic anhydride.

    Science.gov (United States)

    Ohta, H; Ruan, F; Hakomori, S; Igarashi, Y

    1994-11-01

    A simple and sensitive method for quantification of sphingosine in cellular lipid extracts was developed. The assay is based on quantitative conversion of sphingosine to N-[3H]acetylated sphingosine ([3H]C2-ceramide) by N-acylation with [3H]acetic anhydride under certain conditions. Sphingosine was extracted from cultured cells with chloroform and methanol and then treated with base to remove interfering glycerolipids having reactive amino groups (e.g., phosphatidylethanolamine or phosphatidylserine). Sphingosine was acylated with [3H]acetic anhydride in the presence of 0.004 N NaOH. Acylation was complete in 1 h at 37 degrees C when sphingosine was present in the picomole range. After the acylation, samples were treated with NaOH to reduce background radioactivity by removing the remaining [3H]acetic anhydride and hydrolyzing any ester linkages formed during the acylation and resolved by thin-layer chromatography. [3H]C2-ceramide converted from sphingosine with the acylation was detected with radioautography and quantitated by scraping the corresponding band and counting its radioactivity with a scintillation counter. [3H]C2-ceramide formed was quantitatively measured. This assay allows quantification of sphingosine over a range of 10 to 1500 pmol. The amount of sphingosine in lipid extracts from cultured cells was proportional to the number of cells. Sphingosine levels in human gastric cancer KATO III cells, human promyelocytic leukemic HL60 cells, and human monoblastic U937 cells, determined by this method, were 26.6 +/- 2.2, 6.3 +/- 0.4, and 6.8 +/- 0.6 pmol per 10(6) cells, respectively. Our new procedure allows quantification of sphingosine levels present in the low picomole range in lipid extracts from biological samples.

  9. 9 CFR 319.103 - Cured beef tongue.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Cured beef tongue. 319.103 Section 319... Cured beef tongue. In preparing “Cured Beef Tongue,” the application of curing solution to the fresh beef tongue shall not result in an increase in the weight of the cured beef tongue of more than...

  10. Space charge behaviour in maleic anhydride grafted polyethylene/ethylene - vinyl - acetate copolymer laminates

    Science.gov (United States)

    Lee, Seung Hyung; Park, Jung Ki; Han, Jae Hong; Suh, Kwang S.

    1997-01-01

    Charge distributions in maleic anhydride (MAH) grafted polyethylene (g-PE)/ethylene - vinyl - acetate (EVA) copolymer laminates have been measured with materials of different composition. All laminates showed interfacial charge, the polarity and the magnitude of which are explained by interfacial polarization. It was found that the interfacial charge increased with the increase of MAH content in the g-PE, whereas it decreased with the increase of vinyl - acetate content in the EVA. This feature was attributed to the differences in electrical conductivity of the materials. Details of the experimental results are described.

  11. Langmuir and Langmuir-Blodgett films of a maleic anhydride derivative: effect of subphase divalent cations.

    Science.gov (United States)

    Martín-García, B; Velázquez, M Mercedes; Pérez-Hernández, J A; Hernández-Toro, J

    2010-09-21

    We report the study of the equilibrium and dynamic properties of Langmuir monolayers of poly(styrene-co-maleic anhydride) partial 2-buthoxyethyl ester cumene terminated polymer and the effect of the Mg(NO(3))(2) addition in the water subphase on the film properties. Results show that the polymer monolayer becomes more expanded when the electrolyte concentration in the subphase increases. Dense polymer films aggregate at the interface. The aggregates are transferred onto silicon wafers using the Langmuir-Blodgett methodology and the morphology is observed by AFM. The structure of aggregates depends on the subphase composition of the Langmuir film transferred onto the silicon wafer.

  12. Perfluoroalkylation of Unactivated Alkenes with Acid Anhydrides as the Perfluoroalkyl Source.

    Science.gov (United States)

    Kawamura, Shintaro; Sodeoka, Mikiko

    2016-07-18

    An efficient perfluoroalkylation of unactivated alkenes with perfluoro acid anhydrides was developed. Copper salts play a crucial role as a catalyst to achieve allylic perfluoroalkylation with the in situ generated bis(perfluoroacyl) peroxides. Furthermore, carboperfluoroalkylation of alkene bearing an aromatic ring at an appropriate position on the carbon side chain was found to proceed under metal-free conditions to afford carbocycles or heterocycles bearing a perfluoroalkyl group. This method, which makes use of readily available perfluoroalkyl sources, offers a convenient and powerful tool for introducing a perfluoroalkyl group onto an sp(3) carbon to construct synthetically useful skeletons.

  13. Preparation and Crystallization of Carbon Nanotube/maleic Anhydride-grafted Polypropylene Composites

    Institute of Scientific and Technical Information of China (English)

    Xiaohua CHEN; Jing HU; Lingping ZHOU; Wenhua LI; Zi YANG; Yanguo WANG

    2008-01-01

    Carbon nanotube (CNT)/maleic acid anhydride (MAH)-grafted polypropylene (PP) composites were prepared by in situ grafting method. Infrared spectroscopy showed that the CNTs were linked to PP by MAH grafting. The microstructures and calorimetry analysis indicated that the crystallization behaviors of the filled and unfilled PP were quite different. The addition of CNTs dramatically reduced the spherulite size, increased crystallization rate and improved the thermal stability of PP. These results confirmed the expected nucleant effect of CNT on the crystallization of PP. Scanning and transmission electron microscopy showed that the CNTs were dispersed homogeneously, indicating that the original CNT bundles were separated into individual tubes by the grafting.

  14. Electrospun mats from styrene/maleic anhydride copolymers: modification with amines and assessment of antimicrobial activity.

    Science.gov (United States)

    Ignatova, Milena; Stoilova, Olya; Manolova, Nevena; Markova, Nadya; Rashkov, Iliya

    2010-08-11

    New antimicrobial microfibrous electrospun mats from styrene/maleic anhydride copolymers were prepared. Two approaches were applied: (i) grafting of poly(propylene glycol) monoamine (Jeffamine® M-600) on the mats followed by formation of complex with iodine; (ii) modification of the mats with amines of 8-hydroxyquinoline or biguanide type with antimicrobial activity. Microbiological screening against S. aureus, E. coli and C. albicans revealed that both the formation of complex with iodine and the covalent attachment of 5-amino-8-hydroxyquinoline or of chlorhexidine impart high antimicrobial activity to the mats. In addition, S. aureus bacteria did not adhere to modified mats.

  15. POLYMER—SUPPORTED RHODIUM CATALYSTS FOR CARBONYLATION OF METHYL ACETATE TO ACETIC ANHYDRIDE

    Institute of Scientific and Technical Information of China (English)

    CHENDean; HUANGShizhuan; 等

    1993-01-01

    Two kinds of rhodium catalysts supported on cross-linked styrene-divinylbenzene copolymers containing bipyridine or o-phenylene diamine have been prepared and found to display high activity for methyl acetate carbonylation to form acetic anhydride,the activities are even higher than their homogeneous counterparts. XPS analysis was used to characterize the synthetic catalysts.The apparent activation parameters were determined to be Eα=73.3KJ/mol,ΔH≠=66.3KJ/mol,ΔS≠=-28.6eu.These parameters are very close to those in methanol carbonylation and imply to have analogous mechanism in both cases.

  16. Curing agent for polyepoxides and epoxy resins and composites cured therewith. [preventing carbon fiber release

    Science.gov (United States)

    Serafini, T. T.; Delvigs, P.; Vannucci, R. D. (Inventor)

    1981-01-01

    A curing for a polyepoxide is described which contains a divalent aryl radical such as phenylene a tetravalent aryl radical such as a tetravalent benzene radical. An epoxide is cured by admixture with the curing agent. The cured epoxy product retains the usual properties of cured epoxides and, in addition, has a higher char residue after burning, on the order of 45% by weight. The higher char residue is of value in preventing release to the atmosphere of carbon fibers from carbon fiber-epoxy resin composites in the event of burning of the composite.

  17. Synthesis and properties of a bio-based epoxy resin with high epoxy value and low viscosity.

    Science.gov (United States)

    Ma, Songqi; Liu, Xiaoqing; Fan, Libo; Jiang, Yanhua; Cao, Lijun; Tang, Zhaobin; Zhu, Jin

    2014-02-01

    A bio-based epoxy resin (denoted TEIA) with high epoxy value (1.16) and low viscosity (0.92 Pa s, 258C) was synthesized from itaconic acid and its chemical structure was confirmed by 1H NMR and 13C NMR spectroscopy. Its curing reaction with poly(propylene glycol) bis(2-aminopropyl ether) (D230) and methyl hexahydrophthalic anhydride (MHHPA) was investigated. For comparison, the commonly used diglycidyl ether of bisphenol A (DGEBA) was also cured with the same curing agents. The results demonstrated that TEIA showed higher curing reactivity towards D230/MHHPA and lower viscosity compared with DGEBA, resulting in the better processability. Owing to its high epoxy value and unique structure, comparable or better glass transition temperature as well as mechanical properties could be obtained for the TEIA-based network relative to the DGEBA-based network. The results indicated that itaconic acid is a promising renewable feedstock for the synthesis of bio-based epoxy resin with high performance.

  18. Performance of epoxy resin-anhydride pouring materials modified with hyperbranched polyester%超支化聚酯改性环氧-酸酐浇注树脂及性能研究

    Institute of Scientific and Technical Information of China (English)

    井丰喜; 石兆从; 张道洪

    2016-01-01

    The epoxy pouring resin was prepared by using the hydroxyl-terminated hyperbranched polyester, epoxy resin, methyl tetrahydrophthalic anhydride and silica powder as the main materials. The effects of hyperbranched polyester as the addictive on the viscosity, settleability, heat-resistance, mechanical and electrical properties of the cured pouring resin were in detail studied. The results showed that hyperbranched polyester not only increased the heat-resistance, mechanical and electrical properties of the cured pouring resin, but also effectively dispersed the silica powder into the pouring resin and improved the evenness of the mixing system.%采用端羟基超支化聚酯、环氧树脂、甲基四氢苯酐和活性硅微粉为主要材料制备了高性能环氧浇注树脂。研究了超支化聚酯对体系黏度、沉降性、耐温指数、机械性能和电性能的影响及其规律。结果表明,超支化聚酯可有效分散硅微粉,提高混合体系的均匀度,提高浇筑树脂的耐热性、机械强度和电性能。

  19. Curing efficiency of modern LED units.

    Science.gov (United States)

    Rencz, Adam; Hickel, Reinhard; Ilie, Nicoleta

    2012-02-01

    Recent reports claim that modern light-emitting diode (LED) curing units improve curing efficiency by increasing the units' irradiance. In this context also, short polymerisation times up to 5 s are proposed. The aim of this study was to examine whether there are differences in the curing efficiency of modern LED curing units by assessing their effect on two different composite materials and by varying the irradiation time. A nano- and a micro-hybrid resin-based composite (RBC) were polymerised for 5, 10 and 20 s with three commercial and a Prototype LED unit (Elipar™ S10). Cylindrical specimens (6 mm in depth, 4 mm in diameter) were prepared in three increments, each 2-mm thick, and were consecutively cured. Degree of cure was measured for 20 min in real time at the bottom of the samples, starting with the photoinitiation. The micro-mechanical properties (modulus of elasticity, E and Vickers hardness, HV) were measured as a function of depth, in 100-μm steps, on the above described samples stored in distilled water for 24 h at 37°C. Data were analysed with multivariate ANOVA followed by Tukey's test, t test and partial eta-squared statistics. In descending order of the strength of their effect, the type of RBC, depth, polymerisation time and curing unit were significant factors affecting the micro-mechanical parameters (p surface, a minimum of 20 s of irradiation is necessary for an adequate polymerisation 2 mm beyond the surface.

  20. Preparation, characterization and antibacterial activity of octenyl succinic anhydride modified inulin.

    Science.gov (United States)

    Zhang, Xiaoyun; Zhang, Ye-Wang; Zhang, Hongyin; Yang, Qiya; Wang, Haiying; Zhang, Guochao

    2015-01-01

    Octenyl succinic anhydride modified inulin (In-OSA) was synthesized via chemical modification of inulin with octenyl succinic anhydride (OSA). The esterification of inulin with OSA was confirmed by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and degree of substitution (DS) calculation. Antibacterial activity of In-OSA against Staphylococcus aureus and Escherichia coli was investigated by minimum inhibitory concentration (MIC) and inhibition rate determination. The results showed that inhibition rates against both E.coli and S. aureus increased with the increase of the In-OSA concentration. And the MICs against E. coli and S. aureus were 1% and 0.5% (w/v), respectively. The antibacterial mechanism was analyzed with the results of the proteins and nucleic acids leakage, SEM and negative staining transmission electron microscopy (TEM). Both the leakages of proteins and nucleic acids increased with the increase of the In-OSA concentration. The leakage occurred mainly in the early stage which indicated that cell membrane and wall were destroyed by In-OSA quickly. The images of SEM and negative staining TEM suggested that the cell membranes and cell walls of S. aureus were damaged more severely and even destroyed completely; but only pores appeared on the surface of E. coli.

  1. Efficient photochemical generation of peroxycarboxylic nitric anhydrides with ultraviolet light emitting diodes

    Directory of Open Access Journals (Sweden)

    N. D. Rider

    2015-01-01

    Full Text Available Photochemical sources of peroxycarboxylic nitric anhydrides (PANs are utilized in many atmospheric measurement techniques for calibration or to deliver an internal standard. Conventionally, such sources rely on phosphor-coated low-pressure mercury (Hg lamps to generate the UV light necessary to photo-dissociate a dialkyl ketone (usually acetone in the presence of a calibrated amount of nitric oxide (NO and oxygen (O2. In this manuscript, a photochemical PAN source in which the Hg lamp has been replaced by arrays of ultraviolet light-emitting diodes (UV-LEDs is described. The output of the UV-LED source was analyzed by gas chromatography (PAN-GC and thermal dissociation cavity ring-down spectroscopy (TD-CRDS. Using acetone, diethyl ketone (DIEK, diisopropyl ketone (DIPK, or di-n-propyl ketone (DNPK, respectively, the source produces peroxyacetic (PAN, peroxypropionic (PPN, peroxyisobutanoic (PiBN, or peroxy-n-butanoic nitric anhydride (PnBN from NO in high yield (> 90%. Box model simulations with a subset of the Master Chemical Mechanism (MCM were carried out to rationalize products yields and to identify side products. The use of UV-LED arrays offers many advantages over conventional Hg lamp setups, including greater light output over a narrower wavelength range, lower power consumption, and minimal generation of heat.

  2. Grafting of poly (lactic acid) with maleic anhydride using supercritical carbon dioxide

    Science.gov (United States)

    Khankrua, R.; Pivsa-Art, S.; Hiroyuki, H.; Suttiruengwong, S.

    2015-07-01

    The aim of this work was to modify poly lactic acid (PLA) via free radical grafting with maleic anhydride (MA) by using supercritical carbon dioxide (SCCO2). Benzoyl peroxide (BPO) was used as an initiator. The solubility of MA in SCCO2 was first determined to estimate the suitable grafting conditions and equilibrium. From the solubility study of MA in SCCO2, it was found that the solubility of MA in SCCO2 increased with the increasing pressure and dissolution time. PLA films were first prepared by compression molding. The ratio of MA to BPO was 2:1. The reaction temperature and pressure were 70°C and 100 bar respectively. The grafting reaction and the degree of grafting were characterized by nuclear magnetic resonance (NMR) spectroscopy and titration, respectively. Scanning electron microscope (SEM) technique and contact angle were used to confirm the changes in physical properties of PLA film grafted MA. NMR spectrum indicated that the grafting of MA onto PLA was successively achieved. Degree of grafting by using SCCO2 was as high as 0.98%. This provided rather high grafting degree compared with other processes. SEM pictures showed the rough surface structure on modified PLA film. In addition, contact angle results showed an improvement of the hydrophilicity by maleic anhydride grafting onto polymers.

  3. Polycondensation of Tetrahydrofuran with Phthalic Anhydride Induced By a Proton Exchanged Montmorillonite Clay

    Directory of Open Access Journals (Sweden)

    Mohammed Belbachir

    2003-05-01

    Full Text Available Abstract: “Maghnite” a montmorillonite sheet silicate clay, exchanged with protons to produce “H-Maghnite” is an efficient catalyst for polymerization of many vinylic and heterocyclic monomers (Belbachir, M. U.S. Patent. 066969.0101 –2001. The structure compositions of both “Maghnite” and “H-Maghnite” have been developed. This catalyst was used for the polycondensation of the tetrahydrofuran with phthalic anhydride. The polymerization was performed under suitable conditions at temperature (40°C, in presence of acetic anhydride. Experiments revealed that polymerization induced by “H-Maghnite”, proceed in bulk and the conversion increases with increasing “H-Maghnite” proportion.

  4. Synthesis and properties of starch-g-poly(maleic anhydride-co-vinyl acetate

    Directory of Open Access Journals (Sweden)

    2010-01-01

    Full Text Available Starch-g-poly(maleic anhydride-co-vinyl acetate (SMV was synthesized via the esterification reaction of starch with the copolymer of maleic anhydride and vinyl acetate. The carboxylic unit percentage (CUP of SMV was tailored with reaction conditions, and it ranged from 29.8 to 46.9%. The structure and the morphology of the copolymers were characterized with Fourier Transform Infrared spectroscopy and X-ray diffraction analysis. It was found that SMV could form complex with some metal cations such as Ca2+, Pb2+ and Hg2+ or cationic polyelectrolyte chitosan, and precipitate from the solution. The weight of precipitation increases with an increase of the CUP of SMV. In addition, a physically cross-linked hydrogel of SMV/poly(vinyl alcohol (PVA was obtained by freeze/thaw technique. Scanning electron microscopy exhibited the hydrogel was uniform. The gel exhibited pH-responsive re-swelling. The maximum swelling-ratio values of SMV/PVA (9:1, wt/wt gel were 3.29 and 5.34 in HCl (pH 1.0 and phosphate-buffer saline (PBS (pH 12 respectively.

  5. EFFECT OF MALEIC ANHYDRIDE ON KENAF DUST FILLED POLYCAPROLACTONE/THERMOPLASTIC SAGO STARCH COMPOSITES

    Directory of Open Access Journals (Sweden)

    Siang Yee Chang,

    2012-02-01

    Full Text Available The utilization of biodegradable polymers for various applications has been restricted mainly by its high cost. This report aims to study the water absorption and mechanical properties of kenaf dust-filled polycaprolactone/thermoplastic sago starch biodegradable composites as a function of filler loading and treatment with maleic anhydride. While water absorption in untreated biocomposites increased as a function of filler loading, treated biocomposites resulted in weight loss, whereby low molecular weight substances were dissolved into the aging medium. The kenaf dust imparts reinforcing effects on the biocomposites, resulting in improved mechanical properties. This is further attested by morphological studies in which kenaf dust was well dispersed in the polycaprolactone/ thermoplastic sago starch blend matrix. The addition of maleic anhydride into the polycaprolactone/thermoplastic sago starch blend resulted in a homogeneous mixture. At low filler loading, strain at break of the maleated polycaprolactone/thermoplastic sago starch blend increased at the expense of tensile strength and modulus. This is most likely due to the excessive dicumyl peroxide content, which caused chain scission of the polycaprolactone backbone. Tensile strength and modulus improved only when high filler loading was employed.

  6. Flexible Polyimide Aerogel Cross-linked by Poly(maleic Anhydride-alt-alkylene)

    Science.gov (United States)

    Guo, Haiquan; Meador, Mary Ann B.; Wilkewitz, Brittany Marie

    2014-01-01

    Aerogels are potential materials for aerospace applications due to their lower thermal conductivity, lighter weight, and low dielectric constant. However, silica aerogels are restricted due to their inherent fragility, hygroscopic nature, and poor mechanical properties, especially in extreme aerospace environments. In order to fit the needs of aerospace applications, developing new thermal insulation materials that are flexible, and moisture resistant is needed. To this end, we fabricated a series of polyimide aerogels crosslinked with different poly(maleic anhydride-alt-alkylene)s as seen in Scheme 1. The polyimide oligomers were made with 3,3,4,4-biphenyltetracarboxylic dianhydride (BPDA), and different diamines or diamine combinations. The resulting aerogels have low density (0.06 gcm3 to 0.16 gcm3) and high surface area (240-440 m2g). The effect of the different backbone structures on density, shrinkage, porosity, surface area, mechanical properties, moisture resistance and thermal properties will be discussed. These novel polyalkylene-imide aerogels may be potential candidates for applications such as space suit insulation for planetary surface missions, insulation for inflatable structures for habitats, inflatable aerodynamic decelerators for entry, descent and landing (EDL) operations, and cryotank insulation for advance space propulsion systems. Scheme 1. Network of polyimide aerogels crosslinked with deifferent poly(maleic anhydride).

  7. Lysine adducts between methyltetrahydrophthalic anhydride and collagen in guinea pig lung.

    Science.gov (United States)

    Jönsson, B A; Wishnok, J S; Skipper, P L; Stillwell, W G; Tannenbaum, S R

    1995-11-01

    The formation of adducts between methyltetrahydrophthalic anhydride (MTHPA), an important industrial chemical and potent allergen, and collagen from guinea pig lung tissue was investigated. Collagen peptides were obtained from the lung tissue by homogenization, defatting, washing, and digestion with collagenase. In experiments in vitro, lung tissue was exposed to 8.4 mumol (50 microCi) of 14C MTHPA. The amount of adducts was 97 nmol MTHPA/g of wet tissue as determined from the bound radioactivity. In a study in vivo, four guinea pigs were injected intratracheally with 8.4 mumol of 14C MTHPA each. The amount of adducts was 0-1.2 nmol MTHPA/g of wet tissue (determined by bound radioactivity). N epsilon-methyltetrahydrophthaloyl-L-lysine (MTHPL) was synthesized and characterized by NMR, UV, and mass spectrometry (MS). A method to analyze MTHPL, after derivatization with methanol and pentafluorobenzoyl chloride, using gas chromatography-MS was developed. Analysis of Pronase-digested MTHPA-exposed lung tissue showed a concentration of 19 nmol MTHPL/g wet lung in vitro and between 0 and 0.15 nmol MTHPL/g wet lung in vivo. Thus, 20% in vitro and 12-15% in vivo of the bound radioactivity was found as adducts with lysine. These results are a first step toward studies of allergenic epitopes in proteins and methods for biological monitoring of exposure to acid anhydrides.

  8. Pomelo peel modified with acetic anhydride and styrene as new sorbents for removal of oil pollution.

    Science.gov (United States)

    Chai, Wenbo; Liu, Xiaoyan; Zou, Junchen; Zhang, Xinying; Li, Beibei; Yin, Tiantian

    2015-11-01

    Pomelo peel (PP), as one of the well-known agricultural wastes, is cost-effective and environmentally friendly. Based on PP, two new kinds of oil sorbents were prepared by using acetic anhydride and styrene. The structures of raw pomelo peel (RP), acetic anhydride-treated pomelo peel (AP) and styrene-treated pomelo peel (SP) were characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM), contact-angle (CA) measurements. The optimum reaction conditions for preparation of AP and SP were also investigated. The resulting products exhibited better oil sorption capacity than that of RP for diesel and lubricating oil, also SP had better oil sorption capacity than AP, while the oil sorption capacities of SP for diesel and lubricating oil reached 18.91 and 26.36 g/g, respectively. Adsorption kinetics was well described by the pseudo-second-order model. The results indicated that AP and SP, especially SP could be used as the substitute for non-biodegradable oil sorption materials.

  9. Characterization and in vitro degradation of salicylate-derived poly(anhydride-ester microspheres).

    Science.gov (United States)

    Yeagy, Brian A; Prudencio, Almudena; Schmeltzer, Robert C; Uhrich, Kathryn E; Cook, Thomas J

    2006-09-01

    The aim of this study was to investigate how glass transition temperature (Tg) influenced polymer microsphere formation and degradation of three chemically, similar novel salicylatebased poly(anhydride-esters): poly[1,6-bis(o-carboxyphenoxy)hexanoate] (CPH), Tg = 59 degrees C; poly[1,8-bis(o-carboxyphenoxy)octanoate] (CPO), Tg = 30 degrees C; and poly[1,10-bis(ocarboxyphenoxy) decanoate] (CPD), Tg = 27 degrees C. Microspheres of these polymers were prepared using a modified oil-in-water solvent evaporation method and processed by either resuspension or washed by centrifugation. The morphology of the microspheres determined by scanning electron microscopy (SEM) revealed that an extra washing step appears to increase aggregation as the Tg decreases; whereas only limited aggregation occurred in the polymer with the lowest Tg, CPD, in those not washed by centrifugation. Residual polyvinyl alcohol apparently affected the drug release rates from the microspheres by a stabilization process that produced an 8 h lag time and a 5% decrease in the amount of drug released over a 7 day period compared to microspheres washed free of PVA. These results demonstrate that salicylate-based poly(anhydride-esters) with sufficiently high Tgs, can be processed into microspheres that release salicylate over a time period amenable for drug delivery applications.

  10. CHARGE-TRANSFER AND ENERGY-TRANSFER IN THE PHOTO-INDUCED COPOLYMERIZATION OF 2-VINYLNAPHTHALENE WITH MALEIC ANHYDRIDE

    Institute of Scientific and Technical Information of China (English)

    LI Tong; LUO Bin; LI Shanjun; CHU Guobei

    1990-01-01

    The initiation mechanism of the copolymerization of 2-vinylnaphthalene with maleic anhydride was studied under irradiation of 365 nm. The excited complex was formed from ( 1 ) the local excitation of 2-vinylnaphthalene followed by the charge-transfer interaction with maleic anhydride and ( 2 ) the excitation of the ground state charge-transfer complex, and then it collapsed to 1,4-tetramethylene biradical for initiation. A 1:1 alternating copolymer was formed in different monomer feeds. Addition of benzophenone could greatly enhance the rate of copolymerization through energy-transfer mechanism.

  11. SELECTIVE HYDROGENATION OF MALEIC ANHYDRIDE TO Y-BUTYROLACTONE OVER PD/AL(2)O(3) CATALYST USING SUPERCRITICAL CO(2) AS SOLVENT

    Science.gov (United States)

    A selective hydrogenation of maleic anhydride to either y-butyrolactone or succinic anhydride over simple Pd/Al(2)O(3) catalyst under supercritical CO(2) medium is described for the first time which has considerable promise for obht lab-scale as well as industrial selective hydro...

  12. Soluble Synthetic Analogs of Malaria Pigment: Structure of Mesohematin Anhydride [FeIII(MP-IX)]2 and Solution Interaction with Chloroquine

    Energy Technology Data Exchange (ETDEWEB)

    D Bohle; E Dodd; A Kosar; L Sharma; P Stephens; L Suarez; D Tazoo

    2011-12-31

    Changing the vinyl groups of hematin anhydride to either ethyl or hydrogen groups results in increased solubility (Por=porphyrin). Determination of the weak binding constants of the antimalarial drug chloroquine to dimers of these hematin anhydride analogues suggests that solution-phase heme/drug interactions alone are unlikely to be the origin of the action of the drug.

  13. One-step microwave foaming and curing

    Science.gov (United States)

    Gagliani, J.; Lee, R.; Sorathia, U. A. K.; Wilcoxson, A. L.

    1981-01-01

    Process that combines microwave foaming and curing of polyimide precursors in single step produces fire-resistant foam slabs of much larger volume than has previously been possible. By adding selected conductive fillers to powder precursors and by using high-power microwave oven, foam slabs with dimensions in excess of 61 by 61 by 7.6 cm are made. Typical foaming and curing and curing time is 35 minutes in microwave oven with additional 1 to 2 hour postcure in conventional oven.

  14. Thermal curing of an epoxy-anhydride system modified with hyperbranched poly(ethylene imine)s with different terminal groups

    OpenAIRE

    Morancho Llena, José María; Fernández Francos, Xavier; Acebo Gorostiza, Cristina; Ramis Juan, Xavier; Salla Tarragó, José María; Serra Albet, Àngels

    2015-01-01

    Epoxy resins are widely used in applications such as adhesives, coatings, electric laminates, encapsulation of semiconductor devices, matrix material for composites, structural components and cryogenic engineering because of their mechanical properties, adhesion and chemical resistance. However, epoxy resins are inherently brittle due to their high cross-link density. To increase their toughness different modifiers such as rubber, thermoplastic and glass particles can be added, but they al...

  15. Acceleration of curing of resin composite at the bottom surface using slow-start curing methods.

    Science.gov (United States)

    Yoshikawa, Takako; Morigami, Makoto; Sadr, Alireza; Tagami, Junji

    2013-01-01

    The aim of this study was to evaluate the effect of two slow-start curing methods on acceleration of the curing of resin composite specimens at the bottom surface. The light-cured resin composite was polymerized using one of three curing techniques: (1) 600 mW/cm(2) for 60 s, (2) 270 mW/cm(2) for 10 s+0-s interval+600 mW/cm(2) for 50 s, and (3) 270 mW/cm(2) for 10 s+5-s interval+600 mW/cm(2) for 50 s. After light curing, Knoop hardness number was measured at the top and bottom surfaces of the resin specimens. The slow-start curing method with the 5-s interval caused greater acceleration of curing of the resin composite at the bottom surface of the specimens than the slow-start curing method with the 0-s interval. The light-cured resin composite, which had increased contrast ratios during polymerization, showed acceleration of curing at the bottom surface.

  16. [Mineral water as a cure].

    Science.gov (United States)

    Nocco, Priska Binz

    2008-01-01

    The treatment of diseases with mineral spring water belongs to the oldest medical therapies. The "remedy" mineral water is therefore of importance also within the pharmacy. The present pharmacy historical work examines the impact of the use of mineral waters, as well as of their dried components, as therapeutic agents in the 19th and early 20th centuries, i.e. from approx. 1810 to 1930, as well as the contributions given by pharmacists in the development and analysis of mineral water springs. Beside these aspects, the aim here is also to describe the role played by pharmacists in the production of artificial mineral water as well as in the sale and wholesale of natural and artificial mineral water. In the first part of this work the situation in Switzerland and its surrounding countries, such as Germany, France, Italy and Austria, is discussed. The second part contains a case-study of the particular situation in the Canton Tessin. It is known from the scientific literature published at that time that information on mineral water was frequently reported. Starting from the beginning of the 19th century the number of such publications increased tremendously. The major part of them were publications in scientific journals or contributions to medical and pharmaceutical manuals and reference books. In particular the spa-related literature, such as spa-guides, was of growing interest to a broad public. The inclusion of monographs into the Swiss, the Cantonal as well the foreign pharmacopoeias granted a legal frame for the mineral waters and their dried components. These works are of major importance from a pharmacy historical standpoint and represent a unique proof of historical evidence of the old medicinal drug heritage. The most frequently used therapies based on mineral waters were drinking and bath cures. Several diseases, particularly those of a chronic character, were treated with mineral waters. The positive influence of these cures on the recovery of the patients

  17. Light-cured resin for post patterns.

    Science.gov (United States)

    Waldmeier, M D; Grasso, J E

    1992-09-01

    A method of using light-cured acrylic resin as an alternative to the use of chemically-cured acrylic resins with elastomeric impressions for direct post patterns is presented. The GC Unifast LC acrylic resin is a powder/liquid type resin cured by exposure to visible light. The polymerization process has four stages before final curing: slurry, stringy, dough-like (plastic), and rubber-like (elastic). Advantages over current direct and indirect procedures include ease of manipulation of the material and no change in laboratory handling procedures. While in the dough-like state, the material can be contoured. In the rubber-like state, it is flexible to disengage from minor undercut areas.

  18. EFFECT OF SUBSTITUTION POSITION OF HYDROXY GROUP AT BENZOIC ACID ON THE LUMINESCENT AND DEGRADATION PROPERTIES OF POLY[DI(CARBOXYPHENYL) SUCCINATE-co-SEBACIC ANHYDRIDE]S

    Institute of Scientific and Technical Information of China (English)

    Jun Fan; Hong-liang Jiang; Kang-jie Zhu

    2007-01-01

    In this work, two new diacids, di(m-carboxyphenyl) succinate (m-dCPS) and di(o-carboxyphenyl) succinate (o-dCPS), were synthesized by reaction of m-, o-hydroxy benzoic acid with succinic chloride, respectively. Their corresponding copolymers with sebacic acid (SA), P(m-dCPS:SA) and P(o-dCPS:SA), were prepared by melt copolycondensation and characterized by NMR, UV and DSC methods. Compared with inherently fluorescent poly[di(p-carboxyphenyl) succinateco-sebacic anhydride] (P(p-dCPS:SA)), P(m-dCPS:SA) and P(o-dCPS:SA) displayed different luminescent properties. P(m-dCPS:SA) could emit fluorescence under the excitation of both visible and UV light, while P(o-dCPS:SA) could only emit fluorescence when excited with UV light. Degradation rate of the two new copolyanhydrides increased with the increase of SA fraction in the copolymers. In addition, P(o-dCPS:SA) degraded more rapidly than P(m-dCPS:SA) with the same composition. Typical surface-degradation characteristics of these copolyanhydrides were observed.

  19. Fast Curing of Composite Wood Products

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Arthur J. Ragauskas

    2006-04-26

    The overall objective of this program is to develop low temperature curing technologies for UF and PF resins. This will be accomplished by: • Identifying the rate limiting UF and PF curing reactions for current market resins; • Developing new catalysts to accelerate curing reactions at reduced press temperatures and times. In summary, these new curing technologies will improve the strength properties of the composite wood products and minimize the detrimental effects of wood extractives on the final product while significantly reducing energy costs for wood composites. This study is related to the accelerated curing of resins for wood composites such as medium density fiberboard (MDF), particle board (PB) and oriented strandboard (OSB). The latter is frequently manufactured with a phenol-formaldehyde resin whereas ureaformaldehyde (UF) resins are usually used in for the former two grades of composite wood products. One of the reasons that hinder wider use of these resins in the manufacturing of wood composites is the slow curing speed as well as inferior bondability of UF resin. The fast curing of UP and PF resins has been identified as an attractive process development that would allow wood to be bonded at higher moisture contents and at lower press temperatures that currently employed. Several differing additives have been developed to enhance cure rates of PF resins including the use of organic esters, lactones and organic carbonates. A model compound study by Conner, Lorenz and Hirth (2002) employed 2- and 4-hydroxymethylphenol with organic esters to examine the chemical basis for the reported enhanced reactivity. Their studies suggested that the enhance curing in the presence of esters could be due to enhanced quinone methide formation or enhanced intermolecular SN2 reactions. In either case the esters do not function as true catalysts as they are consumed in the reaction and were not found to be incorporated in the polymerized resin product. An

  20. EVALUATION OF DIELECTRIC CURING MONITORING INVESTIGATING LIGHT-CURING DENTAL FILLING COMPOSITES

    Directory of Open Access Journals (Sweden)

    Johannes Steinhaus

    2011-05-01

    Full Text Available The aim of this study is the evaluation of a dielectric analysis (DEA method monitoring the curing behaviour of a light curing dental filling material in real-time. The evaluation is to extract the influence of light intensity on the photo-curing process of dental composite filling materials. The intensity change is obtained by measuring the curing process at different sample depth. It could be shown that increasing sample thickness, and therefore exponentially decreasing light intensity, causes a proportional decrease in the initial curing rate. Nevertheless, the results give rise to the assumption that lower illumination intensities over a long period cause higher overall conversion, and thus better mechanical properties. This would allow for predictions of the impact of different curing-rates on the final mechanical properties.

  1. Effect of cure cycle on curing process and hardness for epoxy resin

    Directory of Open Access Journals (Sweden)

    2009-09-01

    Full Text Available A 3-dimensional finite element model is developed to simulate and analyze the temperature and degree of cure field of epoxy casting part during cure process. The present model based on general finite element software ABAQUS is verified by literature example and experimental data. The numerical results show good agreement with literature example and measured data, and are even more accurate than the simulation of literature. After modeling successfully, the influence of temperature cure cycle ramps have on the temperature and degree of cure gradient is investigated. Moreover, the effect of non-uniform temperature and degree of cure field within epoxy casting part on hardness is demonstrated. The present model provides an accurate and novel method that allows further insight into the process of cure for epoxy resin.

  2. High Power UV LED Industrial Curing Systems

    Energy Technology Data Exchange (ETDEWEB)

    Karlicek, Robert, F., Jr; Sargent, Robert

    2012-05-14

    UV curing is a green technology that is largely underutilized because UV radiation sources like Hg Lamps are unreliable and difficult to use. High Power UV LEDs are now efficient enough to replace Hg Lamps, and offer significantly improved performance relative to Hg Lamps. In this study, a modular, scalable high power UV LED curing system was designed and tested, performing well in industrial coating evaluations. In order to achieve mechanical form factors similar to commercial Hg Lamp systems, a new patent pending design was employed enabling high irradiance at long working distances. While high power UV LEDs are currently only available at longer UVA wavelengths, rapid progress on UVC LEDs and the development of new formulations designed specifically for use with UV LED sources will converge to drive more rapid adoption of UV curing technology. An assessment of the environmental impact of replacing Hg Lamp systems with UV LED systems was performed. Since UV curing is used in only a small portion of the industrial printing, painting and coating markets, the ease of use of UV LED systems should increase the use of UV curing technology. Even a small penetration of the significant number of industrial applications still using oven curing and drying will lead to significant reductions in energy consumption and reductions in the emission of green house gases and solvent emissions.

  3. Cure fraction estimation from the mixture cure models for grouped survival data.

    Science.gov (United States)

    Yu, Binbing; Tiwari, Ram C; Cronin, Kathleen A; Feuer, Eric J

    2004-06-15

    Mixture cure models are usually used to model failure time data with long-term survivors. These models have been applied to grouped survival data. The models provide simultaneous estimates of the proportion of the patients cured from disease and the distribution of the survival times for uncured patients (latency distribution). However, a crucial issue with mixture cure models is the identifiability of the cure fraction and parameters of kernel distribution. Cure fraction estimates can be quite sensitive to the choice of latency distributions and length of follow-up time. In this paper, sensitivity of parameter estimates under semi-parametric model and several most commonly used parametric models, namely lognormal, loglogistic, Weibull and generalized Gamma distributions, is explored. The cure fraction estimates from the model with generalized Gamma distribution is found to be quite robust. A simulation study was carried out to examine the effect of follow-up time and latency distribution specification on cure fraction estimation. The cure models with generalized Gamma latency distribution are applied to the population-based survival data for several cancer sites from the Surveillance, Epidemiology and End Results (SEER) Program. Several cautions on the general use of cure model are advised.

  4. Comparative study on compressive strength of Self cured SCC and Normally cured SCC

    Directory of Open Access Journals (Sweden)

    Ms. Akanksha A. Patil

    2014-11-01

    Full Text Available Curing is the process of maintaining proper moisture content particularly within 28 days to promote optimum cement hydration immediately after placement. Self-compacting concrete is made up of admixture i.e. superplasticizer. In recent years, self-compacting concrete (SCC has gained wide use for placement in congested reinforced concrete structures with difficult casting conditions. Also various curing methods are adopted in the construction industry especially for vertical structures, inaccessible areas s.a. high rise buildings, water scarce areas etc. In such structures conventional curing is not practically possible in most of the cases. But we need efficient curing which improves the strength and durability of concrete. In the present work, comparison of compressive strength of normally cured SCC and SCC cured with self curing material i.e. wax based, white pigmented, membrane forming concrete curing compound has been done. This study is investigating that weather the use of self curing compound is economical or not in remote areas of water without compromising with the compressive strength of concrete.

  5. RAFT copolymerization of itaconic anhydride and 2-methoxyethyl acrylate: a multifunctional scaffold for preparation of “clickable” gold nanoparticles

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Kasama, Takeshi; Jankova, Katja Atanasova

    2013-01-01

    RAFT copolymerization of 2-methoxyethyl acrylate and itaconic anhydride – a monomer derived from renewable resources – is carried out in a controlled fashion. The copolymer allows preparation of gold nanoparticles with abundant surficial carboxyl and alkyne functional groups that are dendronized ...

  6. Kinetics of Hydrolysis of Acetic Anhydride by In-Situ FTIR Spectroscopy: An Experiment for the Undergraduate Laboratory

    Science.gov (United States)

    Haji, Shaker; Erkey, Can

    2005-01-01

    A reaction kinetics experiment for the chemical engineering undergraduate laboratory course was developed in which in-situ Fourier Transfer Infrared spectroscopy was used to measure reactant and product concentrations. The kinetics of the hydrolysis of acetic anhydride was determined by experiments carried out in a batch reactor. The results…

  7. Preparation and structural characterisation of novel and versatile amphiphilic octenyl succinic anhydride-modified hyaluronic acid derivatives

    DEFF Research Database (Denmark)

    Eenschooten, Corinne Diane; Guillaumie, Fanny; Kontogeorgis, Georgios

    2010-01-01

    The purpose of the present study was to prepare amphiphilic hyaluronic acid (HA) derivatives and to study the influence of a selection of reaction parameters on the degree of substitution (DS) of the derivatives. Octenyl succinic anhydride (OSA)–modified HA (OSA–HA) derivatives were prepared...

  8. Positron annihilation lifetime spectroscopy study on the structural relaxation of phenylmethylsiloxane-modified epoxy hybrids at different aging temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Chia-Wen [Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan (China); Ma, Chen-Chi M., E-mail: ccma@che.nthu.edu.tw [Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Tan, Chung-Sung [Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Li, Hsun-Tien [Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan (China)

    2015-07-15

    The cured network conformations and structural relaxation behaviours of the diglycidyl ether of bisphenol A (DGEBA)-methylhexahydrophthalic anhydride (MHHPA) modified with phenylmethylsiloxane-modified epoxy (PMSE) at different aging temperatures were studied using dynamic mechanical analysis (DMA) and positron annihilation lifetime spectroscopy (PALS). The DMA results revealed that the cured PMSE network can insert into the cured DGEBA network to form interpenetrating polymer networks (IPNs). The structural relaxation behaviours of DGEBA–PMSE-0.4 produced using DGEBA, PMSE, and MHHPA at a ratio of 0.6:0.4:1 by equivalent weight were studied using PALS at 150 °C and 55 °C. The aging-induced free volume relaxation parameters of DGEBA–PMSE-0.4 at 150 °C and 55 °C were investigated using the double additive exponential model and the Kohlrausch–Williams–Watts exponential model. For double additive exponential model, only one relaxation time (ζ) of 584.5 h was found at 150 °C; By contrast, there were two separate relaxation times of 37.4 h (ζ{sub 1}) and 753.6 h (ζ{sub 2}) at 55 °C. The ζ{sub 1} of the IPNs hybrid can be attributed to the network relaxation of PMSE, and the ζ{sub 2} can be attributed to the network relaxation of DGEBA at 55 °C. The results suggested the double additive exponential model can effectively predict DGEBA–PMSE hybrid relaxation behaviours. - Highlights: • The cured network conformations of DGEBA–PMSE hybrids were studied using DMA. • The structural relaxation behaviours of DGEBA–PMSE hybrids were studied using PALS. • The cured DGEBA–PMSE hybrids were interpenetrating polymer networks (IPNs). • PALS studies provided a quantitative demonstration of relaxation behaviours. • Double additive exponential model effectively predicted the relaxation times of hybrids.

  9. Electrical breakdown strength results from the EU testing program for potential ITER insulation

    Energy Technology Data Exchange (ETDEWEB)

    Broadbent, A.J.; Crozier, J.; Smith, K.D. [Oxford Instruments, Oxon (United Kingdom)] [and others

    1997-06-01

    Insulation systems will be a key element in the future construction and impregnation of the coils for the ITER device. Electrical barrier layers have been specified to improve the electrical reliability, and this program includes ceramic plasma sprayed coatings, Kapton, Nomex and Mica in conjunction with various Epoxy resins. The electrical breakdown strengths in liquid nitrogen of twenty-two different insulation systems are reported. The final results of this program are presented and compared with the results from a benchmark testing program (insulation system based on anhydride cured DGEBA resin and S2 glass).

  10. Progress on curing of epoxy resin system by cationic initiators%阳离子引发剂在环氧树脂固化体系中的应用研究

    Institute of Scientific and Technical Information of China (English)

    董新; 蔡智奇; 皮丕辉; 文秀芳; 郑大锋; 程江; 杨卓如

    2010-01-01

    讨论了阳离子引发剂催化环氧树脂固化体系反应的原理,综述了新型阳离子引发剂,即镧系金属氟化物在DGEBA、DGEBA/ γ-BL、DGEBA/MCB、DGEBA/MA、DGEBA/PC体系中的作用.浅析了固化促进剂的选用原则,并对镧系金属氟化物在环氧树脂/聚酰胺中的应用前景作了展望.

  11. Ionic liquids as novel solvents for biosynthesis of octenyl succinic anhydride-modified waxy maize starch.

    Science.gov (United States)

    Li, Dandan; Zhang, Xiwen; Tian, Yaoqi

    2016-05-01

    Biosynthesis of octenyl succinic anhydride (OSA) starch was investigated using ionic liquids (ILs) as reaction media. Waxy maize starch was pretreated in 1-butyl-3-methylimidazolium chlorine and then esterified with OSA in 1-octyl-3-methylimidazolium nitrate by using Novozyme 435 as catalyst. The degree of substitution of OSA starch reached 0.0130 with 5 wt% starch concentration and 1 wt% lipase dosage based on ILs weight at 50 °C for 3h. The formation of OSA starch was confirmed by fourier transform infrared spectroscopy. Scanning electron microscopy and X-ray diffraction revealed that the morphology and crystal structure of starch were significantly destroyed. Thermogravimetric analysis showed that esterification decreased the thermal stability of starch. The successful lipase-catalyzed synthesis of OSA starch in ILs suggests that ILs are potential replacement of traditional organic solvents for starch ester biosynthesis.

  12. Polycondensation of Tetrahydrofuran with Phthalic Anhydride Induced By a Proton Exchanged Montmorillonite Clay

    OpenAIRE

    Mohammed Belbachir; Mohammed Issam Ferrahi

    2003-01-01

    Abstract: “Maghnite†a montmorillonite sheet silicate clay, exchanged with protons to produce “H-Maghnite†is an efficient catalyst for polymerization of many vinylic and heterocyclic monomers (Belbachir, M. U.S. Patent. 066969.0101 –2001). The structure compositions of both “Maghnite†and “H-Maghnite†have been developed. This catalyst was used for the polycondensation of the tetrahydrofuran with phthalic anhydride. The polymerization was performed un...

  13. Poly(anhydride-esters) comprised exclusively of naturally occurring antimicrobials and EDTA: antioxidant and antibacterial activities.

    Science.gov (United States)

    Carbone-Howell, Ashley L; Stebbins, Nicholas D; Uhrich, Kathryn E

    2014-05-12

    Carvacrol, thymol, and eugenol are naturally occurring phenolic compounds known to possess antimicrobial activity against a range of bacteria, as well as antioxidant activity. Biodegradable poly(anhydride-esters) composed of an ethylenediaminetetraacetic acid (EDTA) backbone and antimicrobial pendant groups (i.e., carvacrol, thymol, or eugenol) were synthesized via solution polymerization. The resulting polymers were characterized to confirm their chemical composition and understand their thermal properties and molecular weight. In vitro release studies demonstrated that polymer hydrolytic degradation was complete after 16 days, resulting in the release of free antimicrobials and EDTA. Antioxidant and antibacterial assays determined that polymer release media exhibited bioactivity similar to that of free compound, demonstrating that polymer incorporation and subsequent release had no effect on activity. These polymers completely degrade into components that are biologically relevant and have the capability to promote preservation of consumer products in the food and personal care industries via antimicrobial and antioxidant pathways.

  14. Functionalization of poly(dimethylsiloxane) surfaces with maleic anhydride copolymer films.

    Science.gov (United States)

    Cordeiro, Ana L; Zschoche, Stefan; Janke, Andreas; Nitschke, Mirko; Werner, Carsten

    2009-02-01

    Combining advantageous bulk properties of polymeric materials with surface-selective chemical conversions is required in numerous advanced technologies. For that aim, we investigate strategies to graft maleic anhydride (MA) copolymer films onto poly(dimethylsiloxane) (PDMS) precoatings. Amino groups allowing the covalent attachment of the MA copolymer films to the PDMS (Sylgard 184) surface were introduced either by low-pressure ammonia plasma treatment, or by attachment of 3-aminopropyltriethoxysilane (APTES) onto air plasma-treated PDMS. The resultant coatings were extensively characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), contact angle measurements, and atomic force microscopy (AFM). The results show that the impact of the plasma treatment on the physical properties on the topmost surface of the PDMS is critically important for the characteristics of the layered coatings.

  15. Role of Cellulose Nanocrystals on the Microstructure of Maleic Anhydride Plasma Polymer Thin Films.

    Science.gov (United States)

    Brioude, Michel M; Roucoules, Vincent; Haidara, Hamidou; Vonna, Laurent; Laborie, Marie-Pierre

    2015-07-01

    Recently, it was shown that the microstructure of a maleic anhydride plasma polymer (MAPP) could be tailored ab initio by adjusting the plasma process parameters. In this work, we aim to investigate the ability of cellulose nanocrystals (CNCs) to induce topographical structuration. Thus, a new approach was designed based on the deposition of MAPP on CNCs model surfaces. The nanocellulosic surfaces were produced by spin-coating the CNC suspension on a silicon wafer substrate and on a hydrophobic silicon wafer substrate patterned with circular hydrophilic microsized domains (diameter of 86.9 ± 4.9 μm), resulting in different degrees of CNC aggregation. By depositing the MAPP over these surfaces, it was possible to observe that the surface fraction of nanostructures increased from 20% to 35%. This observation suggests that CNCs can act as nucleation points resulting in more structures, although a critical density of the CNCs is required.

  16. Substituted Phthalic Anhydrides from Biobased Furanics: A New Approach to Renewable Aromatics.

    Science.gov (United States)

    Thiyagarajan, Shanmugam; Genuino, Homer C; Śliwa, Michał; van der Waal, Jan C; de Jong, Ed; van Haveren, Jacco; Weckhuysen, Bert M; Bruijnincx, Pieter C A; van Es, Daan S

    2015-09-21

    A novel route for the production of renewable aromatic chemicals, particularly substituted phthalic acid anhydrides, is presented. The classical two-step approach to furanics-derived aromatics via Diels-Alder (DA) aromatization has been modified into a three-step procedure to address the general issue of the reversible nature of the intermediate DA addition step. The new sequence involves DA addition, followed by a mild hydrogenation step to obtain a stable oxanorbornane intermediate in high yield and purity. Subsequent one-pot, liquid-phase dehydration and dehydrogenation of the hydrogenated adduct using a physical mixture of acidic zeolites or resins in combination with metal on a carbon support then allows aromatization with yields as high as 84 % of total aromatics under relatively mild conditions. The mechanism of the final aromatization reaction step unexpectedly involves a lactone as primary intermediate.

  17. Enhanced Activity of Nanocrystalline Beta Zeolite for Acylation of Veratrole with Acetic Anhydride.

    Science.gov (United States)

    Aisha Mahmood Abdulkareem, Al-Turkustani; Selvin, Rosilda

    2016-04-01

    Friedel-Craft acylation of veratrole using homogeneous acid catalysts such as AlCl3, FeCl3, ZnCl2, and HF etc. produces acetoveratrone, (3',4'-dimethoxyacetophenone), which is the intermediate for synthesis of papavarine alkaloids. The problems associated with these homogeneous catalysts can be overcome by using heterogeneous solid catalysts. Since acetoveratrone is a larger molecule, large pore Beta zeolites with smaller particle sizes are beneficial for the liquid-phase acylation of veratrole, for easy diffusion of reactants and products. The present study aims in the acylation of veratrole with acetic anhydride using nanocrystalline Beta Zeolite catalyst. A systematic investigation of the effects of various reaction parameters was done. The catalysts were characterized for their structural features by using XRD, TEM and DLS analyses. The catalytic activity of nanocrystalline Beta zeolite was compared with commercial Beta zeolite for the acylation and was found that nanocrystalline Beta zeolite possessed superior activity.

  18. Synthesis and paste properties of octenyl succinic anhydride modified early Indica rice starch

    Institute of Scientific and Technical Information of China (English)

    SONG Xiao-yan; CHEN Qi-he; RUAN Hui; HE Guo-qing; XU Qiong

    2006-01-01

    Octenyl succinic anhydride (OSA) modified early Indica rice starch was prepared in aqueous slurry systems using response surface methodology. The paste properties of the OSA starch were also investigated. Results indicated that the suitable parameters for the preparation of OSA starch from early Indica rice starch were as follows: reaction period 4 h, reaction temperature 33.4 ℃, pH of reaction system 8.4, concentration of starch slurry 36.8% (in proportion to water, w/w), amount of OSA 3% (in proportion to starch, w/w). The degree of substitution was 0.0188 and the reaction efficiency was 81.0%. The results of paste properties showed that with increased OSA modification, the starch derivatives had higher paste clarity, decreased retrogradation and better freeze-thaw stability.

  19. Oil recovery with sulfomethylated poly (lower alkyl vinyl ether/maleic anhydride)

    Energy Technology Data Exchange (ETDEWEB)

    Norton, C.J.; Falk, D.O.

    1973-05-22

    Lower alkyl vinyl ether e.g., methyl vinyl ether, propyl vinyl ether, isopropyl vinyl ether, hexyl vinyl ether, is copolymerized conventionally with maleic anhydride, the resulting copolymer is treated with ammonia or ammonium hydroxide to form the partial amide-ammonium salt, and this salt is in turn treated with formaldehyde and thereafter or simultaneously with ammonium or alkali metal salt sulfite (including bisulfites, etc.) to form an at least partially sulfomethylated copolymer. Aqueous solutions of the sulfomethylated copolymer are useful in increasing the viscosity of drive fluids used in the supplemented recovery of petroleum from subterranean formations. In general, enhancing the polyionic character of mobility control agents used in supplemented recovery of petroleum provides enhanced recovery. Achieving this enhancement of polyionic character through use of sulfonate groups provides a mobility control agent with good ability to sustain viscosity in the presence of brine and lime, usually present in the connate waters of petroleum-bearing formations. (7 claims)

  20. Synthesis of Poly(aryl amide imide)s Derived from o-diphenyltrimellitic Anhydride

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The synthesis and characterization of a series of novel poly(aryl amide imide)s based on o-diphenyltrimellitic anhydride are described.The poly(aryl amide-imide)s having inherent viscosities of 0.39-1.43dL/g in N-methyl-2-pyrrolidinone at 30℃,were prepared by polymerization with aromatic diamines in N,N-dimethylacetamide and subsequent chemical imidization.All the polymers were amorphous,readily soluble in aprotic polar solvents such as DMAC,NMP,DMF,DMSO,and m-cresol,and could be cast to form flexible and tough films.The glass trsanition temperatures were in the range of 284-336℃,and the temperatures for 5% weight loss in nitrogen were above 468℃.

  1. Dual-Functional Hydrazide-Reactive and Anhydride-Containing Oligomeric Hydrogel Building Blocks.

    Science.gov (United States)

    Kascholke, Christian; Loth, Tina; Kohn-Polster, Caroline; Möller, Stephanie; Bellstedt, Peter; Schulz-Siegmund, Michaela; Schnabelrauch, Matthias; Hacker, Michael C

    2017-02-08

    Biomimetic hydrogels are advanced biomaterials that have been developed following different synthetic routes. Covalent postfabrication functionalization is a promising strategy to achieve efficient matrix modification decoupled of general material properties. To this end, dual-functional macromers were synthesized by free radical polymerization of maleic anhydride with diacetone acrylamide (N-(1,1-dimethyl-3-oxobutyl)acrylamide) and pentaerythritol diacrylate monostearate. Amphiphilic oligomers (Mn 40%). Efficient hydrazide/hydrazine immobilization depending on solution pH, hydrogel ketone content as well as ligand concentration for bioconjugation was shown and reversibility of hydrazone formation was indicated by physiologically relevant hydrazide release over 7 days. Proof-of-concept experiments with hydrazido-functionalized hyaluronan demonstrated potential for covalent aECM immobilization. The presented dual-functional macromers have perspective as reactive hydrogel building blocks for various biomedical applications.

  2. Stereodynamic control of star-epoxy/anhydride crosslinking actuated by liquid-crystalline phase transitions.

    Science.gov (United States)

    Pin, Jean-Mathieu; Mija, Alice; Sbirrazzuoli, Nicolas

    2017-02-07

    The epoxy/anhydride copolymerization kinetics of an original star-epoxy monomer (TriaEP) was explored in dynamic heating mode using a series of isoconversional methods. Negative values of the apparent activation energy (Eα) related to an anti-Arrhenius behavior were observed. The transition from Arrhenius to anti-Arrhenius behavior and vice versa depending on the Eα of polymerization was correlated with the dynamics of mesophasic fall-in/fall-out events, physically induced transition (PIT) and chemically induced transition (CIT). This self-assembly phenomenon induces the generation of an anisotropic crosslinked architecture exhibiting both nematic discotic (ND) and nematic columnar (NC) organization. Particular emphasis was placed on evaluating the juxtaposition/contribution of the liquid-crystalline transitions to crosslinking, considering both the reaction dynamics and the macromolecular vision.

  3. Terpolymerization of 2-ethoxy ethylmethacrylate, styrene and maleic anhydride: determination of the reactivity ratios

    Indian Academy of Sciences (India)

    C S Sanmathi; S Prasannakumar; B S Sherigara

    2004-06-01

    Terpolymerization of 2-ethoxyethyl methacrylate (2-EOEMA), styrene (St) and maleic anhydride (Ma) initiated by benzoyl peroxide was carried out in acetone as common solvent for three monomers. The structure and composition of terpolymer were determined by FTIR spectroscopy by recording analytical absorption bands for St (3002 cm-1), Ma (1781 cm-1) and 2-EOEMA (1261 cm-1) units, respectively. The reactivity ratios for the monomers were calculated according to the general copolymerization equations following the Finnemann–Ross and Kelen–Tudos models. The results show that terpolymerization were carried out through primary ``complex" mechanism at near-binary copolymerization of [St...Ma] complex with 2-EOEMA. Structure of the resulting terpolymer illustrated by 1H-NMR and differential scanning calorimeter showed reduction in g value.

  4. Vegetable oil-derived epoxy monomers and polymer blends: A comparative study with review

    Directory of Open Access Journals (Sweden)

    T. P. Schuman

    2013-03-01

    Full Text Available Glycidyl esters of epoxidized fatty acids derived from soybean oil (EGS and linseed oil (EGL have been synthesized to have higher oxirane content, more reactivity and lower viscosity than epoxidized soybean oil (ESO or epoxidized linseed oil (ELO. The EGS and ESO, for comparison, were used neat and in blends with diglycidyl ether of bisphenol A (DGEBA. Thermosetting resins were fabricated with the epoxy monomers and either BF3 catalyst or anhydride. The curing behaviors, glass transition temperatures, crosslink densities and mechanical properties were tested. The results indicated that polymer glass transition temperatures were mostly a function of oxirane content with additional influence of glycidyl versus internal oxirane reactivity, pendant chain content, and chemical structure and presence of saturated components. EGS provided better compatibility with DGEBA, improved intermolecular crosslinking and glass transition temperature, and yielded mechanically stronger polymerized materials than materials obtained using ESO. Other benefits of the EGS resin blend systems were significantly reduced viscosities compared to either DGEBA or ESO-blended DGEBA counterparts. Therefore, EGS that is derived from renewable sources has improved potential for fabrication of structural and structurally complex epoxy composites, e.g., by vacuum-assisted resin transfer molding.

  5. Fluorescence and Judd-Ofelt analysis of rare earth complexes with maleic anhydride and acrylic acid

    Institute of Scientific and Technical Information of China (English)

    WEN Shipeng; ZHANG Xiaoping; HU Shui; ZHANG Liqun; LIU Li

    2008-01-01

    Two kinds of Eu-complexes, Eu(TTA)2(Phen)(AA) and Eu(TTA)2(Phen)(MA) (HTFA=2-Thenoyltrifluoroacetone, Phen=1,10-phenanthroline, AA=acrylic acid, MA=Maleic anhydride), which combined the excellent fluorescence properties of Eu(TTA)2(Phen)(H2O) and the reactivity of acrylic acid and maleic anhydride with radicals, were synthesized. The two complexes were characterized by elemental analysis, infrared (IR) spectra, and X-ray photoelectron spectroscopy (XPS). Based on the data shown from the fluorescent spectra of the Eu-MA and Eu-AA complexes, the Ωλ (λ=2 and 4) experimental intensity parameters were calculated. The results demonstrated that the Ω2 intensity parameters for the two complexes were smaller than those for the Eu(TTA)2(Phen)(H2O) complex, indicating that a less symmetri-cal chemical environment existed in the complexes. It implied that the radiative efficiency of the 5D0 of these two complexes could be en-hanced by ligand of MA and AA, respectively. The luminescent lifetime of the Eu-AA (τ=7.26×10-4 s) or Eu-MA complex (τ=-8.12×10-4 s) was higher than that of the Eu(TTA)2(Phen)(H2O) complex, which was attributed to the substitution of the water molecule (H2O) in Eu(TTA)2(Phen)(H2O) by the MA or AA ligand.

  6. Interactions of poly (anhydride) nanoparticles with macrophages in light of their vaccine adjuvant properties.

    Science.gov (United States)

    Gamazo, C; Bussmann, H; Giemsa, S; Camacho, A I; Unsihuay, Daisy; Martín-Arbella, N; Irache, J M

    2015-12-30

    Understanding how nanoparticles are formed and how those processes ultimately determine the nanoparticles' properties and their impact on their capture by immune cells is key in vaccination studies. Accordingly, we wanted to evaluate how the previously described poly (anhydride)-based nanoparticles of the copolymer of methyl vinyl ether and maleic anhydride (NP) interact with macrophages, and how this process depends on the physicochemical properties derived from the method of preparation. First, we studied the influence of the desolvation and drying processes used to obtain the nanoparticles. NP prepared by the desolvation of the polymers in acetone with a mixture of ethanol and water yielded higher mean diameters than those obtained in the presence of water (250nm vs. 180nm). In addition, nanoparticles dried by lyophilization presented higher negative zeta potentials than those dried by spray-drying (-47mV vs. -35mV). Second, the influence of the NP formulation on the phagocytosis by J774 murine macrophage-like cell line was investigated. The data indicated that NPs prepared in the presence of water were at least three-times more efficiently internalized by cells than NPs prepared with the mixture of ethanol and water. Besides, lyophilized nanoparticles appeared to be more efficiently taken up by J744 cells than those dried by spray-drying. To further understand the specific mechanisms involved in the cellular internalization of NPs, different pharmacological inhibitors were used to interfere with specific uptake pathways. Results suggest that the NP formulations, particularly, nanoparticles prepared by the addition of ethanol:water, are internalized by the clathrin-mediated endocytosis, rather than caveolae-mediated mechanisms, supporting their previously described vaccine adjuvant properties.

  7. Controlled delivery of paclitaxel from stent coatings using novel styrene maleic anhydride copolymer formulations.

    Science.gov (United States)

    Richard, Robert; Schwarz, Marlene; Chan, Ken; Teigen, Nikolai; Boden, Mark

    2009-08-01

    The controlled release of paclitaxel (PTx) from stent coatings comprising an elastomeric polymer blended with a styrene maleic anhydride (SMA) copolymer is described. The coated stents were characterized for morphology by scanning electron microscopy (SEM) and atomic force microscopy (AFM), and for drug release using high-performance liquid chromatography (HPLC). Differential scanning calorimetry (DSC) was used to measure the extent of interaction between the PTx and polymers in the formulation. Coronary stents were coated with blends of poly(b-styrene-b-isobutylene-b-styrene) (SIBS) and SMA containing 7% or 14% maleic anhydride (MA) by weight. SEM examination of the stents showed that the coating did not crack or delaminate either before or after stent expansion. Examination of the coating surface via AFM after elution of the drug indicated that PTx resides primarily in the SMA phase and provided information about the mechanism of PTx release. The addition of SMA altered the release profile of PTx from the base elastomer coatings. In addition, the presence of the SMA enabled tunable release of PTx from the elastomeric stent coatings, while preserving mechanical properties. Thermal analysis reveled no shift in the glass transition temperatures for any of the polymers at all drug loadings studied, indicating that the PTx is not miscible with any component of the polymer blend. An in vivo evaluation indicated that biocompatibility and vascular response results for SMA/SIBS-coated stents (without PTx) are similar to results for SIBS-only-coated and bare stainless steel control stents when implanted in the non-injured coronary arteries of common swine for 30 and 90 days.

  8. Estudio de la reacción de curado del sistema éter diglicidílico del bisfenol-A (DGEBA y la dietilentriamina (DETA por calorimetría diferencial de barrido

    Directory of Open Access Journals (Sweden)

    González Garcia Filiberto

    2000-01-01

    Full Text Available La reacción de curado del sistema compuesto por el éter diglicidílico del bisfenol-A (DGEBA y la dietilentriamina (DETA fue estudiada por calorimetría diferencial de barrido (DSC. Diferentes expresiones cinéticas fueron encontradas por experimentos isotérmicos y dinámicos las que justifican cambios mecanísticos con la temperatura de cura. La cinética de la reacción cumple un segundo orden cinético con una energía de activación de 90 kJ mol-1 a altas temperaturas (mecanismo no catalítico. La cinética de la reacción a bajas temperaturas manifestó la existencia de dos mecanismos competitivos, se determinaron las constantes de velocidades de reacción a 60 y 70ºC y se encontró una energía de activación en el rango de 56.9 a 63.0 kJ mol¹, que está en perfecto acuerdo con la reportada a bajas temperaturas (mecanismo autocatalítico. También se muestra el diagrama de fases del sistema.

  9. HEAT-RESISTANT COMPOSITES CURED BY ELECTRON BEAM

    Institute of Scientific and Technical Information of China (English)

    Jian-wen Bao; Yang Li; Xiang-bao Chen; Feng-mei Li

    2001-01-01

    Electron beam (EB) curing of composites has many advantages. Heat-resistant EB-curing composites could substitute polyimide composites used in aeronautical engines. In this paper, the effects of catalyst and dose on the cured resin were investigated. The heat-resistance of the resin cured by EB was evaluated by dynamic mechanical analysis (DMA). The experimental results show that the mechanical properties of the composites cured by EB could meet the specifications of aeronautical engines at 250°C.

  10. Assessment of Curing Efficiency and Effect of Moist Curing on Performance of Fly Ash Concrete

    Institute of Scientific and Technical Information of China (English)

    LI Meili; QIAN Jueshi; WANG Lixia; XU Shanshan; JIA Xingwen; FAN Yunyan

    2011-01-01

    This study was conducted to evaluate the sensitivity of compressive strength,water permeability and electrical resistance of near-surface layer concrete with different fly ash contents to curing conditions. It is shown that the sensitivity to curing condition and fly ash content descends in the following order: difference between internal and surface resistivity (ρ)at 28 days, water permeability and compressive strength; both of longer duration of moist curing and use of fly ash in concrete enhanced the water penetration resistance. It is indicated that the resistivity difference p at 28 days can reflect accurately the curing history of fly ash concrete regardless of mix proportions; and use of fly ash in concrete requires longer moist curing duration.

  11. Curing mechanism of flexible aqueous polymeric coatings.

    Science.gov (United States)

    Irfan, Muhammad; Ahmed, Abid Riaz; Dashevskiy, Andriy; Kolter, Karl; Bodmeier, Roland

    2017-02-25

    The objective of this study was to explain curing phenomena for pellets coated with a flexible polymeric coating based on poly(vinyl acetate) (Kollicoat(®) SR 30D) with regard to the effect of starter cores, thickness of drug layer, adhesion of coating to drug-layered-cores as well as coating properties. In addition, appropriate approaches to eliminate the curing effect were identified. Sugar or MCC cores were layered with the model drugs carbamazepine, theophylline, propranolol HCl, tramadol HCl and metoprolol HCl using HPMC (5 or 25% w/w, based on drug) as a binder. Drug-layered pellets were coated with Kollicoat(®) SR 30D in a fluidized bed coater using TEC (10% w/w) as plasticizer and talc (35-100% w/w) as anti-tacking agent. Drug release, pellet properties (morphology, water uptake-weight loss and osmolality) and adhesion of the coating to the drug layer were investigated as a function of curing at 60 °C or 60 °C/75% RH for 24 h. The film formation of the aqueous dispersion of Kollicoat(®) SR 30D was complete, and therefore, a strong curing effect (decrease in drug release) at elevated temperature and humidity (60 °C/75% RH) could not be explained by the well-known hydroplasticization and the further gradual coalescence of the colloidal polymer particles. According to the provided mechanistic explanation, the observed curing effect was associated with 1) high flexibility of coating, 2) adhesion between coating and drug layer, 3) water retaining properties of the drug layer, and 4) osmotically active cores. Unwanted curing effects could be minimized/eliminated by the addition of talc or/and pore-forming water soluble polymers in the coating, increasing binder amount or applying an intermediate coating, by increasing the thickness of drug layer or using non-osmotic cores. A new insight into curing phenomena mainly associated with the adhesion between drug layer and coating was provided. Appropriate approaches to avoid unwanted curing effect were identified.

  12. Prevent and cure disuse bone loss

    Science.gov (United States)

    Jee, Webster S. S.

    1994-01-01

    Anabolic agents like parathyroid hormone and postagladin E-like substances were studied in dogs and rats to determine their effectiveness in the prevention and cure of bone loss due to immobilization. It was determined that postagladin E2 administration prevented immobilization while at the same time it added extra bone in a dose responsive manner. Although bone mass returns, poor trabecular architecture remains after normal ambulation recovery from immobilization. Disuse related bone loss and poor trabecular architecture were cured by post-immobilization postagladin E2 treatment.

  13. Curing kinetics of visible light curing dental resin composites investigated by dielectric analysis (DEA).

    Science.gov (United States)

    Steinhaus, Johannes; Hausnerova, Berenika; Haenel, Thomas; Großgarten, Mandy; Möginger, Bernhard

    2014-03-01

    During the curing process of light curing dental composites the mobility of molecules and molecule segments is reduced leading to a significant increase of the viscosity as well as the ion viscosity. Thus, the kinetics of the curing behavior of 6 different composites was derived from dielectric analysis (DEA) using especially redesigned flat sensors with interdigit comb electrodes allowing for irradiation at the top side and measuring the ion viscosity at the bottom side. As the ion viscosities of dental composites change 1-3 orders of magnitude during the curing process, DEA provides a sensitive approach to evaluate their curing behavior, especially in the phase of undisturbed chain growth. In order to determine quantitative kinetic parameters a kinetic model is presented and examined for the evaluation of the ion viscosity curves. From the obtained results it is seen that DEA might be employed in the investigation of the primary curing process, the quality assurance of ingredients as well as the control of processing stability of the light curing dental composites.

  14. Light-Cured Self-Etch Adhesives Undergo Hydroxyapatite-Triggered Self-Cure.

    Science.gov (United States)

    Liu, Y; Bai, X; Liu, Y W; Wang, Y

    2016-03-01

    Light cure is a popular mode of curing for dental adhesives. However, it suffers from inadequate light delivery when the restoration site is less accessible, in which case a self-cure mechanism is desirable to salvage any compromised polymerization. We previously reported a novel self-cure system mediated by ethyl 4-(dimethylamino)-benzoate (4E) and hydroxyapatite (HAp). The present work aims to investigate if such self-cure phenomenon takes place in adhesives that underwent prior inadequate light cure and to elucidate if HAp released from the dental etching process is sufficient to trigger it. Model self-etch adhesives were formulated with various components, including bis[2-methacryloyloxy)ethyl]-phosphate (2MP) as acidic monomer and trimethylbenzoyl-diphenylphosphine oxide (TPO) as photoinitiator. In vitro evolution of degree of conversion (DC) of HAp-incorporated adhesives was monitored by infrared spectroscopy during light irradiation and dark storage. Selected adhesives were allowed to etch and extract HAp from enamel, light-cured in situ, and stored in the dark, after which Raman line mapping was used to obtain spatially resolved DC across the enamel-resin interface. Results showed that TPO+4E adhesives reached DC similar to TPO-only counterparts upon completion of light irradiation but underwent another round of initiation that boosted DC to ~100% regardless of HAp level or prior light exposure. When applied to enamel, TPO-only adhesives had ~80% DC in resin, which gradually descended to ~50% in enamel, whereas TPO+4E adhesives consistently scored ~80% DC across the enamel-resin interface. These observations suggest that polymerization of adhesives that underwent insufficient light cure is salvaged by the novel self-cure mechanism, and such salvaging effect can be triggered by HAp released from dental substrate during the etching process.

  15. Effect of maleic anhydride-aniline derivative buffer layer on the properties of flexible substrate heterostructures: Indium tin oxide/nucleic acid base/metal

    Energy Technology Data Exchange (ETDEWEB)

    Stanculescu, A., E-mail: sanca@infim.ro [National Institute of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, 077125, Bucharest-Magurele (Romania); Socol, M. [National Institute of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, 077125, Bucharest-Magurele (Romania); Socol, G.; Mihailescu, I.N. [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG-36, 077125, Bucharest-Magurele (Romania); Girtan, M. [Laboratoire de Photonique d' Angers, Universite d' Angers, 2, Bd. Lavoisier, 49045, Angers (France); Preda, N. [National Institute of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, 077125, Bucharest-Magurele (Romania); Albu, A.-M. [Department of Polymer Science, University ' Politehnica' of Bucharest, Bucharest (Romania); Stanculescu, F. [University of Bucharest, Faculty of Physics, Str. Atomistilor nr.405, P.O. Box MG-11, Bucharest-Magurele, 077125 (Romania)

    2011-12-01

    This paper presents some investigations on the properties of guanine (G) and cytosine (C) based heterostructures deposited on flexible substrates. The effects of two types of maleic anhydride-aniline derivatives (maleic anhydride-cyano aniline or maleic anhydride-2,4 dinitroaniline) buffer layer, deposited between indium tin oxide and (G) or (C) layer, on the optical and electrical properties of the heterostructures have been identified. The heterostructures containing a film of maleic anhydride-2,4 dinitroaniline have shown a good transparency and low photoluminescence in visible range. This buffer layer has determined an increase in the conductance only in the heterostructures based on (G) and (C) deposited on biaxially-oriented polyethylene terephthalate substrate.

  16. Modular access to vicinally functionalized allylic (thio)morpholinonates and piperidinonates by substrate-controlled annulation of 1,3-azadienes with hexacyclic anhydrides.

    Science.gov (United States)

    Braunstein, Hannah; Langevin, Spencer; Khim, Monique; Adamson, Jonathan; Hovenkotter, Katie; Kotlarz, Lindsey; Mansker, Brandon; Beng, Timothy K

    2016-09-21

    A modular substrate-controlled hexannulation of inherently promiscuous 1,3-azadienes with hexacyclic anhydrides, which affords versatile vicinally functionalized allylic lactams, in high yields, regio- and stereoselectivities is described.

  17. Creep measurements on curing epoxy systems

    DEFF Research Database (Denmark)

    Kammer, Charlotte; Szabo, Peter

    1998-01-01

    The chemical curing of a stoichiometric mixture of the diglycidyl ether of bisphenol A and a 1,3-bis-(aminomethyl)-cyclohexane is studied.Creep experiments are combined with measurements in a Differential Scanning Calorimeter (DSC) to determine the change in bulk viscosity due to network formation....

  18. Mechanical characterization and modeling of curing thermosets

    NARCIS (Netherlands)

    Van 't Hof, C.

    2006-01-01

    Chemical shrinkage and simultaneous build-up of mechanical properties in curing thermosets leads to the build-up of residual stresses and strains. Depending on the constraints these may cause interface failure, dimensional inaccuracy or failure in the thermoset or its surrounding structure. The pre

  19. Grafting amino drugs to poly(styrene-alt-maleic anhydride) as a potential method for drug release

    Energy Technology Data Exchange (ETDEWEB)

    Khazaei, Ardeshir; Saednia, Shahnaz; Saien, Javad; Abbasi, Fatemeh, E-mail: Khazaei_1326@yahoo.com, E-mail: ssaednia@gmail.com [Faculty of Chemistry, Bu-Ali Sina University, Hamedan (Iran, Islamic Republic of); Kazem-Rostami, Masoud [Young Researchers Club and Elite, Takestan Branch, Islamic Azad University, Takestan (Iran, Islamic Republic of); Sadeghpour, Mahdieh [Department of Chemistry, Takestan Branch, Islamic Azad University, Takestan (Iran, Islamic Republic of); Borazjani, Maryam Kiani [Faculty of Science, Department of Chemistry, Bushehr Payame Noor University (PNU), Bushehr (Iran, Islamic Republic of)

    2013-07-15

    Drug delivery systems based on polymer-drug conjugates give an improved treatment with lower toxicity or side effects and be used for the treatment of different diseases. Conjugates of biodegradable poly(styrene-alt-maleic anhydride) (PSMA), with a therapeutic agents such as amantadine hydrochloride, amlodipine, gabapentin, zonisamide and mesalamine, were afforded by the formation of the amide bonds of the amino drugs that reacted with the PSMA anhydride groups. The amounts of covalently conjugated drugs were determined by a {sup 1}H NMR spectroscopic method, and the in vitro release rate in buffer solution (pH 1.3) was studied at body temperature 37 Degree-Sign C. In kinetic studies, different dissolution models were examined to obtain drug release data and the collected data were well-fitted to the Korsmeyer-Peppas equation, revealing a dominant Fickian diffusion mechanism for drug release under the in vitro conditions. (author)

  20. Facile and Efficient Acetylation of Primary Alcohols and Phenols with Acetic Anhydride Catalyzed by Dried Sodium Bicarbonate

    Directory of Open Access Journals (Sweden)

    Fulgentius Nelson Lugemwa

    2013-12-01

    Full Text Available A variety of primary alcohols and phenols were reacted with acetic anhydride at room temperature in the presence of sodium bicarbonate to produce corresponding esters in good to excellent yields. The acetylation of 4-nitrobenzyl alcohol was also carried out using other bicarbonates and carbonates. The reaction in the presence of cesium bicarbonate and lithium carbonate gave 4-nitrobenzyl acetate in excellent yield, while in the presence of Na2CO3, K2CO3, Cs2CO3, or KHCO3 the yield was in the range of 80%–95%. Calcium carbonate and cobaltous carbonate did not promote the acetylation of 4-ntirobenzyl alcohol using acetic anhydride. The acetylation of 4-nitrobenzyl alcohol was carried out using ethyl acetate, THF, toluene, diethyl ether, dichloromethane and acetonitrile, and gave good yields ranging from 75%–99%. Toluene was the best solvent for the reaction, while diethyl ether was the poorest.

  1. Structure and Properties of Polymer Interphases.

    Science.gov (United States)

    1986-12-01

    bisphenol-A epoxy (16). The adhesive used with the aluminum substrates consisted of a low molecular weight DGEBA epoxy resin (Epon 828, Shell Chemical...to nitrogen and that the reaction between TETA and DGEBA epoxies involves mostly the primary * amines of the curing agent. Figure 7B shows the C(ls...hydroxyl groups present in the cured DGEBA resin. The formation of amine hydrochlorides with residual HC1, a byprodu:t of the preparation of DGEBA resins

  2. The Reaction of Crotonic Anhydride with Scots and Corsican Pine: Investigation of Kinetic Profiles and Determination of Activation Energies

    OpenAIRE

    Özmen, Nilgül; ÇETİN, Nihat Sami

    2014-01-01

    The kinetics of the reaction of crotonic anhydride with Scots pine (Pinus sylvestris) and Corsican pine (Pinus nigra) using pyridine as catalyst/solvent was investigated and activation energies for the initial reaction determined. Activation energies were calculated from the Arrhenius equation using rate data obtained from time-course experiments repeated at several temperatures. In one method, reaction constants (k) were determined experimentally, while in the other method initial rates were...

  3. Relationship between global indices of reactivity, electrodonating and electroaccepting powers, and the hammet constant in isatoic anhydride derivatives

    Indian Academy of Sciences (India)

    J S Durand-Niconoff; L Cruz-Kuri; M H Matus; J Correa-Basurto; J S Cruz-Sánchez; F R Ramos-Morales

    2011-09-01

    The possible correlation between Hammett’s constant (p), a characteristic parameter of functional groups with electrodonating or electroaccepting properties, and two indices of global reactivity were calculated in the gas phase. Parameters associated to a set of 22 structural variants of isatoic anhydride (2-3, 1-benzoxazin-2,4(1)-dione, ISA), replaced with diverse functional groups, were explored applying linear and quadratic statistical models for numerical analysis of the results.

  4. Ficusmicrochlorin A-C, two new methoxy lactone chlorins and an anhydride chlorin from the leaves of Ficus microcarpa.

    Science.gov (United States)

    Lin, Huan-You; Chiu, Hsi-Lin; Lu, Te-Ling; Tzeng, Chih-Ying; Lee, Tzong-Huei; Lee, Ching-Kuo; Shao, Yi-Yuan; Chen, Chiy-Rong; Chang, Chi-I; Kuo, Yueh-Hsiung

    2011-01-01

    Two new methoxy lactone chlorins ficusmicrochlorin A (1) and ficusmicrochlorin B (2), and one new anhydride chlorin ficusmicrochlorin C (3), along with eight known pheophytins were isolated from the leaves of Ficus microcarpa. Their structures were determined by the extensive 1D- and 2D-NMR techniques. New pheophytin compound was rarely obtained from natural sources. In the past ten years, only three new natural pheophytins were characterized.

  5. A NOVEL COPOLYMER-BOUND CIS- DICARBONYLRHODIUM COMPLEX FOR THE CARBONYLATION OF METHANOL TO ACETIC ACID AND ACETIC ANHYDRIDE

    Institute of Scientific and Technical Information of China (English)

    YUAN Guoqing; CHEN Yuying; CHEN Rongyao

    1989-01-01

    A series of porous microspheres of linear and ethylene diacrylate (M ') cross-linked copolymers of 2 - vinylpyridine (V) and methyl acrylate (M) reacted with tetracarbonyldichlorodirhodium to form a series of cis-dicarbonylrhodium chelate complex (MVRh and MVM 'Rh). They are thermally stable yet very reactive in the carbonylation of methanol to acetic acid, and of methanol - acetic acid mixture to acetic acid and acetic anhydride with a selectivity of 100% under relatively mild and anhydrous conditions.

  6. 新型有机硅多元胺环氧树脂固化剂结构与性能%Structure and properties of novel silicone polyamine as epoxy resin curing agents

    Institute of Scientific and Technical Information of China (English)

    曹骏; 李诚; 范宏

    2014-01-01

    In this paper,three silicone polyamines APS,SFA and PSPA were applied to cure the epoxy resin E51 (DGEBA), and their mechanical and adhesive properties were tested and compared with the traditional aliphatic amines such as ethylenediamine, hexamethylene diamine and polyether amine(HUNTSMAN D230).It was found that the epoxy resin cured with silicone polyamines exhibited excellent bending strength,impact strength and heat resistance properties.Based on the bonding tests for iron plates,the silicone polyamines/epoxy resin adhesives showed higher adhesion strength and water resistance than that of using above traditional aliphatic amines as the curing agents.The phenyl containing silicone polyamine (PSPA)/epoxy resin adhesive revealed the highest adhesion strength among them,reached 14.8 MPa.%评价了3种有机硅多元胺(APS、SFA和PSPA )分别固化环氧树脂E51(DGEBA)时,固化物的力学性能和粘接强度,并与常见脂肪胺类固化剂[乙二胺、己二胺、聚醚胺(D-230)]作了对比。固化物基体力学和热性能测试表明,有机硅多元胺环氧固化物表现出较佳的冲击强度、弯曲强度和热稳定性。有机硅多元胺/环氧树脂胶粘剂的铁片粘接强度以及耐水性明显高于脂肪胺/环氧胶粘剂体系,其中含苯基有机硅多元胺作为固化剂时粘接强度最高,达到14.8 MPa。

  7. Preparation and characterization of porous titania-grafted poly(styrene-divinylbenzene)/maleic anhydride nanocomposite microspheres

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Mesoporous titania-grafted poly(styrene-divinylbenzene)/maleic anhydride [P(St-DVB)/MA] nanocomposite microspheres were prepared by an open ring reaction method.The titania nanoparticles were first modified by attachment of amino groups to their surface to prevent particle aggregation,and to allow the nanoparticles to covalently bond the polymer microspheres,the surface of which was modified by attachment of MA functional groups to enable the polymer to retain their porous structures and to react with the amino groups on the surface of the titania particles.The porous nanocomposite microspheres were detected by FTIR,SEM,TEM,XRD and UV-Vis spectrophotometry.The results indicated that the nanocomposite microspheres were composed of nanosized titania uniformly distributed on the surface,and exhibited better UV absorbing property than pure polymer microspheres or unmodified titania.Furthermore,compared with pure porous polymer microspheres,the nanocomposite microspheres showed more efficient UV protection and slow release of Parsol-1789(a photo-reactive and cosmetic agent) held inside the porous network of the microspheres.

  8. Structural properties of pepsin-solubilized collagen acylated by lauroyl chloride along with succinic anhydride.

    Science.gov (United States)

    Li, Conghu; Tian, Zhenhua; Liu, Wentao; Li, Guoying

    2015-10-01

    The structural properties of pepsin-solubilized calf skin collagen acylated by lauroyl chloride along with succinic anhydride were investigated in this paper. Compared with native collagen, acylated collagen retained the unique triple helix conformation, as determined by amino acid analysis, circular dichroism and X-ray diffraction. Meanwhile, the thermostability of acylated collagen using thermogravimetric measurements was enhanced as the residual weight increased by 5%. With the temperature increased from 25 to 115 °C, the secondary structure of native and acylated collagens using Fourier transform infrared spectroscopy measurements was destroyed since the intensity of the major amide bands decreased and the positions of the major amide bands shifted to lower wavenumber, respectively. Meanwhile, two-dimensional correlation spectroscopy revealed that the most sensitive bands for acylated and native collagens were amide I and II bands, respectively. Additionally, the corresponding order of the groups between native and acylated collagens was different and the correlation degree for acylated collagen was weaker than that of native collagen, suggesting that temperature played a small influence on the conformation of acylated collagen, which might be concluded that the hydrophobic interaction improved the thermostability of collagen.

  9. Granular size of potato starch affects structural properties, octenylsuccinic anhydride modification and flowability.

    Science.gov (United States)

    Wang, Chan; Tang, Chuan-He; Fu, Xiong; Huang, Qiang; Zhang, Bin

    2016-12-01

    Native potato starch (PS) granules were separated into three size fractions: larger than 30μm (P-L), 15-30μm (P-M), and smaller than 15μm (P-S). The morphological and crystalline structure of fractionated potato starches were investigated by light and scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The P-L fraction showed ellipsoidal shape and B-type X-ray pattern, whereas the P-S fraction had spherical shape and A-type pattern. The fluorophore-assisted capillary electrophoresis data showed that the P-L fraction had more B2 chains and less short A and B1 chains than the P-S counterparts. Smaller granules with larger specific surface area had higher degree of substitution when reacted with octenylsuccinic anhydride (OSA), and showed more uniform distribution of octenylsuccinate substituents. Both OSA modified and unmodified P-S samples showed higher flowability compared with the P-L counterparts.

  10. Acetylation of Wood Flour from Four Wood Species Grown in Nigeria Using Vinegar and Acetic Anhydride

    Directory of Open Access Journals (Sweden)

    Yakubu Azeh

    2013-01-01

    Full Text Available Effect of acetylation on pretreated wood flour of four different wood species, Boabab (Adansonia digitata, Mahoganny (Daniella oliveri, African locust bean (Parkia biglobosa and Beech wood (Gmelina arborea, had been investigated. The first batch of wood species were acetylated using acetic anhydride while the second batch were acetylated with commercial vinegar. Both experiments were conducted in the presence of varying amount of CaCl2 as catalyst and at temperature of 120°C for 3 h. The success of acetylation was determined based on Weight Percent Gain for each sample treated with either chemicals used. FT-IR, a veritable tool was used for the analysis of both treated and untreated samples to further investigate the success of acetylation. The results showed the presence of important band such as carbonyl absorptions at 1743, 1744, 1746, 1731, 1718 and 1696 cm−1 as appeared separately in the spectra of acetylated samples, confirming esterification occurred. The purpose of this work was to investigate the applicability of vinegar for acetylation of lignocellulosic fibers. Blends/composites were prepared by solution casting and their kinetics investigated in distilled water. The results indicated they could be used in outdoor applications such as, decking and packaging.

  11. RING OPENING COPOLYMERIZATION OF SUCCINIC ANHYDRIDE-ETHYLENE OXIDE BY Al (Ⅲ) ORGANOMETALLIC CATALYSTS

    Institute of Scientific and Technical Information of China (English)

    CHEN Xianhai; ZHANG Yifeng; SHEN Zhiquan

    1997-01-01

    Ring opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO)was successfully carried out by using a series of aluminum-based catalyst in 1,4-dioxane at 62±2℃. The results showed that in-situ AlR3-H2O (R=ethyl, iso-butyl) catalysts gave higher molecular weight ((-M)w ~ 104), while Al(OR)3 catalysts gave the higher alternating copolymer structure with slightly lower molecular weight. The in-situ AlR3-H2O systems have been evaluated in more detail for the reaction which showed the optimum H2O/Al molar ratio to be 0.5. The copolymers with different composition (FSA/FEO = 36/64 to 45/55 mol/mol) were synthesized by using different monomer feed ratio. The melting point (Tm), glass transition temperature (Tg) and enthalpy of fusion (ΔHf) of these copolymers are depended on the copolymer composition and in the range of 87~ 102℃,-12 ~ -18℃, and 37 ~ 66J/g, respectively. The second heating scan of DSC also indicated that the higher alternating copolymer was more easily recrystallized. The onset decomposition temperature was more than 300℃ under nitrogen and influenced by the copolymer composition.

  12. Morphology and Mechanical Properties of Nylon 6/PBT Blends Compatibilized with Styrene/Maleic Anhydride Copolymer

    Institute of Scientific and Technical Information of China (English)

    QIN Shu-hao; YU Jie; ZHENG Qiang; HE Min; ZHU Hong

    2007-01-01

    The mechanical properties and dynamic mechanical properties of blends composed of Nylon 6 and poly( butylenes terephthalate) (PBT), with styrene/maleic anhydride(SMA) as compatibilizer, were studied. The observation on the morphologies of the etched surfaces of the cryogenically fractured specimens via scanning electron microscopy(SEM)demonstrated that in the compatibilized Nylon 6/PBT blends, there exists a finer and more uniform dispersion induced by thein-situ interfacial chemical reactions during the preparation than that in the corresponding uncompatibilized blends. On the other hand, the overall mechanical properties of the compatibilized blends could be remarkably improved compared with those of the uncompatibilized ones. Moreover, increasing the amount of the compatibilizer SMA leads to a more efficient dispersion of the PBT phase in Nylon 6/PBT blends. Furthermore, there exists an optimum level of SMA added to achieve the maximum mechanical properties. As far as the mechanism of this reactive compatibilization is concerned, the enhanced interfacial adhesion is necessary to obtain improved dispersion, stable phase morphology, and better mechanical properties.

  13. Reaction of octenylsuccinic anhydride with a mixture of granular starch and soluble maltodextrin.

    Science.gov (United States)

    Bai, Yanjie; Shi, Yong-Cheng

    2013-11-06

    The reaction of octenylsuccinic anhydride (OSA) with a mixture of granular waxy maize starch and soluble maltodextrin was investigated. OSA was reacted with a 1:1 (w/w) mixture of the granular starch and maltodextrin at OSA levels of 1.5, 3, 9, and 15% (wt% based on starch weight). After the first 0.5h of the reaction, degree of substitution (DS) on maltodextrin reached 0.021, 0.030, 0.080, and 0.10 for 1.5, 3, 9, and 15% OSA, respectively, whereas DS for granular starch was only 0.0020, 0.0087, 0.014, and 0.016. At 2h of the reaction, the bound OS ratio of maltodextrin to granular starch was 10.8 when OSA concentration was 1.5% and the ratio decreased to ca. 5 at higher OSA concentrations. OSA preferred to react with maltodextrin than semi-crystalline granular starch when both existed in the system. OSA reacted with maltodextrin at a much faster rate and to a greater extent than with granular starch, but a significant amount of OSA reacted with granular starch at 3-15% OSA concentrations.

  14. Dodecenylsuccinic anhydride derivatives of gum karaya (Sterculia urens): preparation, characterization, and their antibacterial properties.

    Science.gov (United States)

    Padil, Vinod Vellora Thekkae; Senan, Chandra; Černík, Miroslav

    2015-04-15

    Esterifications of the tree-based gum, gum karaya (GK), using dodecenylsuccinic anhydride (DDSA) were carried out in aqueous solutions. GK was deacetylated using alkali treatment to obtain deacetylated gum karaya (DGK). The DGK and its DDSA derivative were characterized using gel permeation chromatography/multiangle laser light scattering (GPC/MALLS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), proton nuclear magnetic resonance spectroscopy ((1)H NMR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) analysis, and rheological studies. The degree of substitution was found to be 10.25% for DGK using (1)H NMR spectroscopy. The critical aggregation concentration of DDSA-DGK was determined using dye solubilization and surface tension methods. The antibacterial activity of the DDSA-DGK derivative was then investigated against Gram-negative Escherichia coli and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus. The DDSA-DGK derivative has the potential for use as a stabilizing agent in food and nonfood applications. It can also be developed as an antibacterial agent.

  15. Separation of maleic anhydride grafted polypropylene using multidimensional high-temperature liquid chromatography.

    Science.gov (United States)

    Prabhu, K N; Macko, T; Brüll, R; Remerie, K; Tacx, J; Garg, P; Ginzburg, A

    2016-04-01

    Functionalization addresses a property gap of polyolefins and opens new perspectives due to improved surface properties in applications like composites (e.g., glass fiber reinforced polypropylene) and anti-corrosive coatings for metals. Various techniques have been developed to characterize functionalized polyolefins, yet no analytical approach addressing their chemical heterogeneity exists. Using High Temperature Size Exclusion Chromatography (HT-SEC) coupled to infrared spectroscopy we could show for two model samples of polypropylene grafted maleic anhydride (PP-g-MA), differing in their nominal MA content, that the grafting density increases with decreasing molar mass. Crystallization Analysis Fractionation (CRYSTAF) does not enable to separate these samples according to their composition to the extent required. Yet, when using High Temperature High Performance Liquid Chromatography (HT-HPLC), with either silica gel or Mica as stationary phase and a gradient mobile phase, a deformulation into a grafted and a non-grafted fraction could be achieved. This was confirmed by analyzing the eluted fractions by infrared spectroscopy. Hyphenating the separation according to composition with a separation according to molar mass (HT-HPLC x HT-SEC) enabled for the first time to reveal the bivariate distribution of PP-g-MA with regard to the molar mass and composition. Using on-line infrared detection quantitative information on the compositional and molar mass parameters of the individual fractions could be obtained.

  16. Position of modifying groups on starch chains of octenylsuccinic anhydride-modified waxy maize starch.

    Science.gov (United States)

    Bai, Yanjie; Kaufman, Rhett C; Wilson, Jeff D; Shi, Yong-Cheng

    2014-06-15

    Octenylsuccinic anhydride (OSA)-modified starches with a low (0.018) and high (0.092) degree of substitution (DS) were prepared from granular native waxy maize starch in aqueous slurry. The position of OS substituents along the starch chains was investigated by enzyme hydrolysis followed by chromatographic analysis. Native starch and two OS starches with a low and high DS had β-limit values of 55.9%, 52.8%, and 34.4%, respectively. The weight-average molecular weight of the β-limit dextrin from the OS starch with a low DS was close to that of the β-limit dextrin from native starch but lower than that of the β-limit dextrin from the OS starch with a high DS. Debranching of OS starches was incomplete compared with native starch. OS groups in the OS starch with a low DS were located on the repeat units near the branching points, whereas the OS substituents in the OS starch with a high DS occurred both near the branching points and the non-reducing ends.

  17. An efficient acetylation of dextran using in situ activated acetic anhydride with iodine

    Directory of Open Access Journals (Sweden)

    MUHAMMAD A. HUSSAIN

    2010-02-01

    Full Text Available A facile, efficient, cost-effective and solvent-free acetylation method has been developed for the acetylation of dextran. Dextran acetates were successfully synthesized using different molar ratios of acetic anhydride in the presence of iodine as a catalyst without the use of any solvent. The reactions were realized at 50 °C for 3 h under stirring and nitrogen. This efficient method yielded highly pure and organosoluble dextran esters. The reaction appears highly effective for obtaining higher degrees of substitution (DS with great efficiency. Under solvent-free conditions, dextran triacetates were efficiently synthesized. It was also observed that the molar ratio can easily control the DS of pendant groups onto the polymer backbone. Hence, a range of products with varying DS were successfully designed, purified and characterized. Covalent attachment of the pendant groups onto the polymer backbone was verified by spectroscopic techniques. Thermogravimetric analysis indicated that the obtained dextran esters were thermally as stable as dextran. The DS of the pendant groups onto the polymer backbone was calculated using standard acid base titration after saponification. Furthermore, all products were thoroughly characterized by thermal analysis (TG and DTG, and FTIR and 1H-NMR spectroscopic analysis.

  18. THERMAL properties and morphology of Polypropylene/Polycarbonate/Polypropylene-Graft-Maleic anhydride blends

    Directory of Open Access Journals (Sweden)

    Mat-Shayuti M. S.

    2016-01-01

    Full Text Available This work investigates the effect of blending polycarbonate (PC into polypropylene (PP matrix polymer on thermal properties and morphology. The blends, containing 5% to 35% of polycarbonate and 5% compatibilizer, were compounded using twin-screw extruder and fabricated into standard tests samples using injection or compression molding. The compatibilizer used was polypropylene-graft-maleic anhydride (PP-g-MA. Thermogravimetric analysis (TGA showed improved thermal degradation temperature of PP/PC/PP-g-MA blends compared to pure PP. As PC content increased, the thermal degradation temperature also improved. The highest improvement of thermal degradation temperature was 23.3%, demonstrated by 60/35/5 composition. It was found that the thermal stability of PP/PC blends was improved with the addition of PP-g-MA. PP-g-MA was suspected to enhance the phase adhesion between PP and PC, thus improving thermal stability. Microscopy analysis showed PC reinforcement phase existed as particulates dispersed in PP matrix phase. PC also was in irregular shapes of fibers or flakes in certain compositions, depending on PC fraction and compatibilizer content.

  19. Effect of maleic anhydride treatment on the mechanical properties of sansevieria fiber/vinyl ester composites

    Science.gov (United States)

    Pradipta, Rangga; Mardiyati, Steven, Purnomo, Ikhsan

    2017-03-01

    Sanseviera trifasciata commonly called mother-in-law tongue also known as snake plant is native to Indonesia, India and Africa. Sansevieria is a new fiber in composite research and has showed promising properties as reinforcement material in polymer matrix composites. Chemical treatment on reinforcing fiber is crucial to reduce hydrophilic tendency and thus improve compatibility with the matrix. In this study, effect of maleic anhydride as chemical treatment on the mechanical properties of Sansevieria fiber/vinyl ester composite was investigated. Sansevieria fibers were immersed by using NaOH 3% for two hours at 100°C and then treated by using maleic anhydrate for two hours at 120°C. Composites were prepared by solution casting with various volume fractions of fiber; 0%, 2.5%, 5%, 7.5% and 10%. Actual density, volume fraction of void and mechanical properties of composite were conducted according to ASTM standard testing methods D792, D3171 and D3039. It was found that mechanical properties of composites increased as volume fractions of fiber was increased. The highest tensile strength and modulus of elasticity of composites were 57.45 MPa and 3.47 GPa respectively, obtained from composites with volume fraction of fiber 10%.

  20. Locally delivered salicylic acid from a poly(anhydride-ester): impact on diabetic bone regeneration.

    Science.gov (United States)

    Wada, Keisuke; Yu, Weiling; Elazizi, Mohamad; Barakat, Sandrine; Ouimet, Michelle A; Rosario-Meléndez, Roselin; Fiorellini, Joseph P; Graves, Dana T; Uhrich, Kathryn E

    2013-10-10

    Diabetes mellitus (DM) involves metabolic changes that can impair bone repair, including a prolonged inflammatory response. A salicylic acid-based poly(anhydride-ester) (SA-PAE) provides controlled and sustained release of salicylic acid (SA) that locally resolves inflammation. This study investigates the effect of polymer-controlled SA release on bone regeneration in diabetic rats where enhanced inflammation is expected. Fifty-six Sprague-Dawley rats were randomly assigned to two groups: diabetic group induced by streptozotocin (STZ) injection or normoglycemic controls injected with citrate buffer alone. Three weeks after hyperglycemia development or vehicle injection, 5mm critical sized defects were created at the rat mandibular angle and treated with SA-PAE/bone graft mixture or bone graft alone. Rats were euthanized 4 and 12weeks after surgery, then bone fill percentage in the defect region was assessed by micro-computed tomography (CT) and histomorphometry. It was observed that bone fill increased significantly at 4 and 12weeks in SA-PAE/bone graft-treated diabetic rats compared to diabetic rats receiving bone graft alone. Accelerated bone formation in normoglycemic rats caused by SA-PAE/bone graft treatment was observed at 4weeks but not at 12weeks. This study shows that treatment with SA-PAE enhances bone regeneration in diabetic rats and accelerates bone regeneration in normoglycemic animals.

  1. Radical coupling of maleic anhydride onto graphite to fabricate oxidized graphene nanolayers

    Indian Academy of Sciences (India)

    Fatemeh Samadaei; Mehdi Salami-Kalajahi; Hossein Roghani-Mamaqani

    2016-02-01

    Radical coupling was used to modify graphite with maleic anhydride (MAH). Azobisisobutyronitrile (AIBN) as radical generator activated MAH radically and it was reacted with defects at the surface of nanolayers. A set of batches with different reaction times (24, 48 and 72 h) were performed to obtain fully-modified nanolayers (GMA1, GMA2 and GMA3, respectively). Fourier transform infrared results approved the synthesis of MAHgrafted graphite. Thermogravimetric analysis showed that 5.9, 11.1 and 13.2 wt% of MAH was grafted onto the surface of GMA1, GMA2 and GMA3, respectively, and that was approved by X-ray photoelectron spectroscopy results. Also, X-ray diffraction patterns showed that $d$-spacing increased from 0.34 nm for graphite to 1.00 nm for all modified samples. However, GMA1 showed a weak peak related to graphite structure that disappeared when reaction time was increased. After modification with MAH, lamella flake structure of graphite was retained whereas the edges of sheets became distinguishable as depicted by scanning electron microscopy images. According to Raman spectra, modification progression resulted in more disorder structure of nanolayers due to grafting of MAH. Also, transmission electron microscopy images showed graphite as transparent layers while after modification, surface of nanolayers became folded due to the opposite effects of $\\pi$-conjugated domains and electrostatic repulsion of oxygen-containing groups.

  2. Cantharidin and its anhydride-modified derivatives: relation of structure to insecticidal activity.

    Science.gov (United States)

    Sun, Wenbo; Liu, Zhongyi; Zhang, Yalin

    2012-12-20

    Cantharidin is a natural compound of novel structure with ideal insecticidal activity. However, the relationship of structure to insecticidal activity of cantharidin and its derivatives has not been ever clarified. To explore what determines the insecticidal activity structurally of cantharidin-related compounds, two series target compounds 6 and 7 were synthesized by replacing the anhydride ring of norcantharidin with an aromatic amine or fatty amine with different electron density, respectively. The structures of these compounds were characterized by 1H NMR, 13C NMR and HRMS-ESI. A bioassay showed that compounds 6 (a-m) lacked any larvicidal activity against Plutella xylostella; whereas their ring-opened partners 7 (a-m) provided a variety of larvicidal activities against P. xylostella, and compound 7f indicated the highest larvicidal activity with LC(50) value of 0.43 mM. The present work demonstrated that the form of the compound (cyclic or ring-opened) or their ability to hydrolyze facilely was the key to determine whether it exhibits larvicidal activity. Moreover, it revealed that the improvement of insecticidal activity required a reasonable combination of both aliphatic amide and aromatic amide moieties, and the type of substituent Y on the aniline ring was critical.

  3. Thermal and Cure Kinetics of Epoxy Molding Compounds Cured with Thermal Latency Accelerators

    Directory of Open Access Journals (Sweden)

    Chean-Cheng Su

    2013-01-01

    Full Text Available The cure kinetics and mechanisms of a biphenyl type epoxy molding compounds (EMCs with thermal latency organophosphine accelerators were studied using differential scanning calorimetry (DSC. Although the use of triphenylphosphine-1,4-benzoquinone (TPP-BQ and triphenylphosphine (TPP catalysts in biphenyl type EMCs exhibited autocatalytic mechanisms, thermal latency was higher in the TPP-BQ catalyst in EMCs than in the TPP catalyst in EMCs. Analyses of thermal characteristics indicated that TPP-BQ is inactive at low temperatures. At high temperatures, however, TPP-BQ increases the curing rate of EMC in dynamic and isothermal curing experiments. The reaction of EMCs with the TPP-BQ latent catalyst also had a higher temperature sensitivity compared to the reaction of EMCs with TPP catalyst. In resin transfer molding, EMCs containing the TPP-BQ thermal latency accelerator are least active at a low temperature. Consequently, EMCs have a low melt viscosity before gelation, and the resins and filler are evenly mixed in the kneading process. Additionally, flowability is increased before the EMCs form a network structure in the molding process. The proposed kinetic model adequately describes curing behavior in EMCs cured with two different organophosphine catalysts up to the rubber state in the progress of curing.

  4. Bond strength of a light-cured and two auto-cured glass ionomer liners.

    Science.gov (United States)

    Holtan, J R; Nystrom, G P; Olin, P S; Rudney, J; Douglas, W H

    1990-10-01

    Ninety-nine extracted human molar teeth were used in this study comparing the shear bond strengths on dentine of one light-cured and two auto-cured polyalkenoate (glass ionomer) cements. Bond strength can be influenced by differences in tooth structure. A balanced-incomplete block design (Hull and Nie, 1981) was used to reduce variation attributable to such differences. Cements were applied to paired dentine surfaces in combinations such that 66 tooth sides were treated with each material. A light-cured dentinal adhesive and composite resin restorative material were then placed and shear bond strength testing was conducted exactly 24 h after the completion of each specimen. Mean forces (MPa) for the three materials were compared using an appropriate analysis of variance model (balanced-incomplete-blocks) The shear bond strengths (MPa) of the light-cured liner (Espe, Seefeld/Oberbay, FRG) was 4.71 +/- 1.16. Vitrabond showed the greatest variance of all three materials tested, however this material's average bond strength was greater than the maximum achieved for the other materials. Student-Newman-Keuls comparison of means showed that all cements differed significantly from each other (alpha = 0.05). It is concluded that the light-cured glass ionomer liner exhibited significantly better shear bond strength performance than the two auto-cured glass ionomers tested.

  5. [Dimensional accuracy of microwave-cured denture base resin].

    Science.gov (United States)

    Uchida, K; Okamoto, F; Ogata, K; Sato, T

    1989-02-01

    Recently, microwave-cured denture base resin was developed, and the resin solved the problem of internal porosity which had been generated by curing the conventional denture base resins with microwave irradiation. In this study, the dimensional accuracy of microwave-cured denture base resin was compared with that of other denture base resins, such as pour-type resin, heat-cured resin and heat-shock resin. From the experiment, the following results were obtained. 1. Dimensional accuracy of microwave-cured denture base resin was better than that of heat-cured resin and heat-shock resin, and was similar to that of pour-type resin. 2. Dimensional accuracy of microwave-cured denture base resin by slow cooling method and rapid cooling method was almost the same. Those findings suggest that microwave-cured denture base resin is valuable in clinic.

  6. Effect of curing on clinical retention. A 7-year evaluation

    DEFF Research Database (Denmark)

    van Dijken, Jan WV; Pallesen, Ulla

    Objective: To evaluate in a prospective evaluation the retention of Class V compomer and hybrid resin composite restorations placed with a 1-step self etch system and cured with continuous, soft-start and pulse-delay curing. Methods: 139 Class V restorations were placed and cured at random in 60...... subjects with a compomer (Dyract AP;68) or resin composite (Tetric Ceram:67) and cured for 40s with continuous, soft-start and pulse-delay modes. The restorations were evaluated with slightly modified USPHS criteria yearly during 7 years. Results: Of 135 restorations evaluated at 7 years, 29 were lost, 17...... compomer (25%) and 12 Tetric Ceram (18%). The cumulative loss rates for the compomer and resin composite restorations cured with the three curing modes were. continuous cure: 26.1%/18.2%, soft-start: 22.7%/19.0%, pulse delay: 26.1%/16.7%. No statistical difference were seen between the curing modes...

  7. Drinking Peroxide as 'Natural' Cure Leads to Dangerous Blood Clots

    Science.gov (United States)

    ... https://medlineplus.gov/news/fullstory_163513.html Drinking Peroxide as 'Natural' Cure Leads to Dangerous Blood Clots ... 9, 2017 (HealthDay News) -- Ingesting high-concentration hydrogen peroxide as a "natural cure" or cleansing agent may ...

  8. Electron Beam Curing of Polymer Matrix Composites - CRADA Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Janke, C. J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Howell, Dave [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Norris, Robert E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    1997-05-01

    The major cost driver in manufacturing polymer matrix composite (PMC) parts and structures, and one of the elements having the greatest effect on their quality and performance, is the standard thermal cure process. Thermal curing of PMCs requires long cure times and high energy consumption, creates residual thermal stresses in the part, produces volatile toxic by-products, and requires expensive tooling that is tolerant of the high cure temperatures.

  9. 7 CFR 29.6002 - Air-cured.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Air-cured. 29.6002 Section 29.6002 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6002 Air-cured. Tobacco cured under natural atmospheric...

  10. Reaction kinetics of piperylene and maleic anhydride%间戊二烯和顺酐反应动力学

    Institute of Scientific and Technical Information of China (English)

    雷昊; 杨阿三; 孙勤; 程榕; 郑燕萍

    2011-01-01

    The reaction of C5 and maleic anhydride to synthesize crude methyltetrahydrophthalic anhydride (MTHPA) is a key step in the production of MTHPA and methylhexahydrophthalic anhydride (MHHPA). The reaction kinetics of piperylene and maleic anhydride under the appropriate solvent was studied. Single-factor multilevel experiment was conducted to show the effects of the initial mole ratio (0.4-1. 1 )of maleic anhydride to piperylene, reaction temperature(1545 t), and solvents (MTHPA, toluene and acetone)on the reaction, and the kinetics data of piperylene and maleic anhydride reaction was determined. Based .on the basic mechanisms of Diels-Alder reaction, a kinetics model was established. By regressing experimental data to a linear fitting based on numerical calculation method, the activation energy and pre-exponential factor were obtained with methyl tetrahydrophthalic anhydride, toluene and acetone as solvents. The results show that the reaction process accords with second-order reaction; different solvents have little influence on activation energy, but have great influences on the pre-exponential factor, in which the activation energy and pre-exponential factor approach the highest values when MTHPA is used as solvent.%C5和顺酐反应合成粗甲基四氢苯酐是生产甲基四氢苯酐及甲基六氢苯酐的关键步骤.为了研究C5中间戊二烯与顺酐反应动力学,选择合适溶剂并设计单因素多水平方案,考察了顺酐与间戊二烯摩尔比(0.4-1.1)、反应温度( 15-45℃)、溶剂(甲基四氢苯酐、甲苯和丙酮)等因素对反应的影响,测定了间戊二烯与顺酐反应的动力学数据.依据Diels-Alder反应的基本原理,建立了动力学模型.利用数值计算方法对实验数据进行线性拟合,分别得到了以甲基四氢苯酐、甲苯和丙酮为溶剂时的活化能和指前因子,结果表明反应符合二级反应.不同溶剂对反应的活化能影响较小,对指前因子影响较大,其中以甲基

  11. Alternative cancer cures: "unproven" or "disproven"?

    Science.gov (United States)

    Vickers, Andrew

    2004-01-01

    Oncology has always coexisted with therapies offered outside of conventional cancer treatment centers and based on theories not found in biomedicine. These alternative cancer cures have often been described as "unproven," suggesting that appropriate clinical trials have not been conducted and that the therapeutic value of the treatment is unknown. Contrary to much popular and scientific writing, many alternative cancer treatments have been investigated in good quality clinical trials, and they have been shown to be ineffective. In this article, clinical trial data on a number of alternative cancer cures including Livingston-Wheeler, Di Bella Multitherapy, antineoplastons, vitamin C, hydrazine sulfate, Laetrile, and psychotherapy are reviewed. The label "unproven" is inappropriate for such therapies; it is time to assert that many alternative cancer therapies have been "disproven."

  12. Cure of HCV related liver disease.

    Science.gov (United States)

    Shiffman, Mitchell L; Benhamou, Yves

    2015-01-01

    Chronic hepatitis C virus (HCV) causes chronic liver injury and can lead to cirrhosis and hepatocellular carcinoma (HCC). HCV can also interact with the immune system to cause several HCV related disorders including essential mixed cryoglobulinemia, vasculitis, dermatitis, glomerulonephritis and lymphoma. A strong association between HCV and diabetes mellitus also exists. These extrahepatic features may lead to increased fatigue and a reduced quality of life. It is now possible to cure most patients with chronic HCV using oral antiviral therapy. Many of these HCV-related disorders and symptoms can be cured when HCV is eradicated. However, some patients may have irreversible injury to extrahepatic sites, cirrhosis that cannot resolve, an increased risk for HCC, persistent fatigue and a reduced quality of life, despite achieving sustained virological response.

  13. Curing Reaction Model of Epoxy Asphalt Binder

    Institute of Scientific and Technical Information of China (English)

    QIAN Zhendong; CHEN Leilei; WANG Yaqi; SHEN Jialin

    2012-01-01

    In order to understand the strength developing law of the epoxy asphalt mixture,a curing reaction model of the epoxy asphalt binder was proposed based upon the thermokinetic analysis.Given some assumptions,the model was developed by applying the Kissinger law as well as Arrhenius equation,and the differential scanning calorimetry was performed for estimating the model parameters.To monitor the strength development of the epoxy asphalt mixture,a strength test program was employed and then results were compared to those produced from the proposed model.The comparative evaluation shows that a good consistency exists between the outputs from test program and the proposed model,indicating that the proposed model can be used effectively for simulating the curing reaction process for the epoxy asphalt binder and predicting the strength development for the epoxy asphalt mixture.

  14. Contactless optoelectronic technique for monitoring epoxy cure.

    Science.gov (United States)

    Cusano, A; Buonocore, V; Breglio, G; Calabrò, A; Giordano, M; Cutolo, A; Nicolais, L

    2000-03-01

    We describe a novel noninvasive optical technique to monitor the refractive-index variation in an epoxy-based resin that is due to the polymerization process. This kind of resin is widely used in polymer matrix composites. It is well known that the process of fabricating a thermoset-based composite involves mass and heat transfer coupled with irreversible chemical reactions that induce physical changes. To improve the quality and the reliability of these materials, monitoring the cure and optimization of the manufacturing process are of key importance. We discuss the basic operating principles of an optical system based on angle deflection measurements and present typical cure-monitoring results obtained from optical characterization. The method provides a flexible, high-sensitivity, material-independent, low-cost, noninvasive tool for monitoring real-time refractive-index variation.

  15. Light-Curing Adhesive Repair Tapes

    Science.gov (United States)

    Allred, Ronald; Haight, Andrea Hoyt

    2009-01-01

    Adhesive tapes, the adhesive resins of which can be cured (and thereby rigidized) by exposure to ultraviolet and/or visible light, are being developed as repair patch materials. The tapes, including their resin components, consist entirely of solid, low-outgassing, nonhazardous or minimally hazardous materials. They can be used in air or in vacuum and can be cured rapidly, even at temperatures as low as -20 C. Although these tapes were originally intended for use in repairing structures in outer space, they can also be used on Earth for quickly repairing a wide variety of structures. They can be expected to be especially useful in situations in which it is necessary to rigidize tapes after wrapping them around or pressing them onto the parts to be repaired.

  16. Fast curing ethylene vinyl acetate films with dual curing agent towards application as encapsulation materials for photovoltaic modules

    Directory of Open Access Journals (Sweden)

    W-H. Ruan

    2014-02-01

    Full Text Available To speed up curing of ethylene vinyl acetate (EVA films as encapsulation materials for photovoltaic modules, a dual curing agent of benzoyl peroxide (BPO and butylperoxy 2-ethylhexyl carbonate (TBEC was introduced in this work. The experimental results indicated that for the weight ratio of BPO/TBEC of 0.6/2.4, over 80% gel content of EVA was yielded after curing at 130°C for 12 min. Compared with the case of single curing agent, the present one obviously operated at much lower temperature with faster rate. By carefully studying the influence of curing agent proportion and curing conditions on gel content of EVA films, as well as rheology and curing kinetics, the mechanism involved was analyzed and verified. The results are believed to be useful for developing new curing system of EVA encapsulation films with improved processability.

  17. Using Sex to Cure the Genome.

    Directory of Open Access Journals (Sweden)

    Eduardo P C Rocha

    2016-03-01

    Full Text Available The diversification of prokaryotes is accelerated by their ability to acquire DNA from other genomes. However, the underlying processes also facilitate genome infection by costly mobile genetic elements. The discovery that cells can uptake DNA by natural transformation was instrumental to the birth of molecular biology nearly a century ago. Surprisingly, a new study shows that this mechanism could efficiently cure the genome of mobile elements acquired through previous sexual exchanges.

  18. Coating and curing apparatus and methods

    Energy Technology Data Exchange (ETDEWEB)

    Brophy, Brenor L.; Gonsalves, Peter R.; Maghsoodi, Sina; Colson, Thomas E.; Yang, Yu S.; Abrams, Ze' ev R.

    2016-04-19

    Disclosed is a coating apparatus including flow coating and roll-coating that may be used for uniform sol-gel coating of substrates such as glass, solar panels, windows or part of an electronic display. Also disclosed are methods for substrate preparation, flow coating and roll coating. Lastly, systems and methods for curing sol-gel coatings deposited onto the surface of glass substrates using high temperature air-knives, infrared emitters and direct heat applicators are disclosed.

  19. Photothermal Monitoring Of Curing Of Polymers

    Science.gov (United States)

    Rooney, Michael

    1993-01-01

    Time-resolved infrared radiometry (TRIR) adapted to monitoring curing of some polymers in production. Proposal part of continuing effort to perfect production of hydroxy-terminated polybutadiene for use in liners of solid-fuel rocket motors. Applicable to monitoring changing states of many other materials in process. TRIR, non-contact technique implemented with remotely situated equipment and better suited to use in production.

  20. Sage Gene Expression Profiles Characterizing Cure

    Science.gov (United States)

    2006-10-01

    therapies to improve breast cancer cure frequency. Down Regulation of VEGF in MTCL Cells. RNA interference has been a powerful genetic tool to study...Science 296, 550 (2002). 100. D. A. Rubinson et al., Nat Genet 33, 401 (2003). 101. E. Devroe, P. A. Silver, BMC Biotechnol 2 (2002). 102. J. P...double- plotted along the estrous cycle. Double plotting of rhythmic patterns is a standard chronobiological technique that allows visualization of

  1. An investigation on the effect of light cure and self cure composite resins on bonding strength of light cure glass ionomer to dentin (In-vitro

    Directory of Open Access Journals (Sweden)

    Pahlavan A

    2004-02-01

    Full Text Available Composite reins have recently become popular for posterior teeth restorations. Gap"nformation and subsequent microleakage are of the complications resulting from such restorations. One of the"ntechniques to overcome polymerization shrinkage of composite resins is sandwich technique (application of"nglass ionomer as a base beneath the composite resin. Since polymerization patterns in two types of composite"nresins (light cure and self cure differ from each other, various effects on the bond strength between glass"nionomer and dentin are expected."nPurpose: The aim of this in vitro study was to evaluate the effects of self- cure and light- cure composite"nresins in sandwich technique on the bond strength of light cure glass ionomer and dentin."nMaterials and Methods: 40 extracted human premolars were selected and divided into four groups:"nGroup 1: Light cure glass ionomer of 1mm thickness was placed on dentin."nGroup 2: 1mm thickness of light cure glass ionomer plus a mass of self cure composite resin of 2mm"nthickness were placed."nGroup 3: 1mm thickness of light cure glass ionomer plus light cure composite resin as two separate 1mm layer"nwere placed."nGroup 4: 1mm thickness of light cure glass ionomer with 37% phosphoric acid etching followed by two"nseparate layers of light cure composite resin of 1 mm thickness were placed."nSEM was used to determine gap size ai Gl- dentin and Gi- composite interlaces. The findings were analyzed"nby ANOVA and t-student tests."nResults: Groups 1 and 2 showed no gap at Gl-dentm interface and also cracks were not observed in all these"nspecimens. In group 3, there was gap between light cure GI and light cure composite resin and cracks were"nseen in GI, too. Group 4 showed gap at both interfaces and more cracks were seen in GI. Groups I and 2"nshowed the least gap formation and group 4 showed the most. Statistically significant difference was found"nbetween groups 3, 4 and group 1 (control, 2."nConclusion: Base

  2. Cure Behavior and Thermal Properties of Diepoxidized Cardanol Resin Cured by Electron Beam Process

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Donghwan; Cheon, Jinsil [Kumoh National Institute of Technology, Gumi (Korea, Republic of)

    2013-07-01

    Thermal curing of epoxy resin requires high temperature, time-consuming process and the volatilization of hardener. It has known that electron beam curing of epoxy resin is a fast process and occurs at low or room temperature that help reduce residual mechanical stresses in thermosetting polymers. Diepoxidized cardanol (DEC) can be synthesized by an enzymatic method from cashew nut shell liquid (CNSL), that constitutes nearly one-third of the total nut weight. A large amount of CNSL can be formed as a byproduct of the mechanical processes used to render the cashew kerneledible and its total production approaches one million tons annually, which can be bio-degradable and replace the industrial thermosetting plastics. It is expected that DEC may be cured as in an epoxy resin, which was constituted on two epoxide group and long alkyl chain, and two-types of onium salts (cationic initiator) were used as a photo-initiator. The experimental variables of this study are type and concentration of photo-initiators and electron beam dosage. In this study, the effects of initiator type and concentration on the cure behavior and the thermal properties of DEC resin processed by using electron beam technology were studied using FT-IR, TGA, TMA, DSC, and DMA. Figure 1 is the FT-IR results, showing the change of chemical structure of pure DEC and electron beam cured DEC. The characteristic absorption peak of epoxide group appeared at 850cm{sup -1}. The shape and the height were reduced when the sample was irradiated with electron beam. From this result, the epoxide groups is DEC were opened by electron beam and cured. After then, electron beam cured DEC was investigated the effect of forming 3-dimensional network.

  3. 丁二酸酐性能及各种生产工艺介绍%The Properties and Various Production Technology of Succinic Anhydride

    Institute of Scientific and Technical Information of China (English)

    潘玉莹; 李江; 胡利娜; 肖鹏飞

    2014-01-01

    Succinic anhydride was a kind of widely used and important fine chemical raw materials , especially its derivatives of high value -added fine chemical products , succinic anhydride production process in all the world mainly divided into succinic acid dehydration and maleic anhydride hydrogenated to succinic anhydride .The properties, the application and production technology of succinic anhydride , and comparison of production technology , maleic anhydride melting catalytic hydrogenated to succinic anhydride were mainly introduced , which was one of the most competitive and promising development method due to the cost of production and the comprehensive energy consumption was low .%丁二酸酐是一种重要的精细化工原料,用途广泛,尤其它的衍生物更是附加值高的精细化工产品,全球丁二酸酐的生产工艺主要有丁二酸脱水法、顺丁烯二酸酐催化加氢法。本文章主要介绍了丁二酸酐的性能、用途和生产工艺技术,并对生产工艺技术进行了比较,顺丁烯二酸酐熔融催化加氢法由于生产成本和综合能耗较低,是最具竞争力,发展前景看好的一种方法。

  4. Accurate Cure Modeling for Isothermal Processing of Fast Curing Epoxy Resins

    Directory of Open Access Journals (Sweden)

    Alexander Bernath

    2016-11-01

    Full Text Available In this work a holistic approach for the characterization and mathematical modeling of the reaction kinetics of a fast epoxy resin is shown. Major composite manufacturing processes like resin transfer molding involve isothermal curing at temperatures far below the ultimate glass transition temperature. Hence, premature vitrification occurs during curing and consequently has to be taken into account by the kinetic model. In order to show the benefit of using a complex kinetic model, the Kamal-Malkin kinetic model is compared to the Grindling kinetic model in terms of prediction quality for isothermal processing. From the selected models, only the Grindling kinetic is capable of taking into account vitrification. Non-isothermal, isothermal and combined differential scanning calorimetry (DSC measurements are conducted and processed for subsequent use for model parametrization. In order to demonstrate which DSC measurements are vital for proper cure modeling, both models are fitted to varying sets of measurements. Special attention is given to the evaluation of isothermal DSC measurements which are subject to deviations arising from unrecorded cross-linking prior to the beginning of the measurement as well as from physical aging effects. It is found that isothermal measurements are vital for accurate modeling of isothermal cure and cannot be neglected. Accurate cure predictions are achieved using the Grindling kinetic model.

  5. Elucidation of substituted ester group position in octenylsuccinic anhydride modified sugary maize soluble starch.

    Science.gov (United States)

    Ye, Fan; Miao, Ming; Huang, Chao; Lu, Keyu; Jiang, Bo; Zhang, Tao

    2014-12-01

    The octenylsuccinic groups in esterification-modified sugary maize soluble starches with a low (0.0191) or high (0.0504) degree of substitution (DS) were investigated by amyloglucosidase hydrolysis followed by a combination of chemical and physical analysis. The results showed the zeta-potential remained at approximately the same value regardless of excessive hydrolysis. The weight-average molecular weight decreased rapidly and reached 1.22 × 10(7) and 1.60 × 10(7) g/mol after 120 min for low-DS and high-DS octenylsuccinic anhydride (OSA) modified starch, respectively. The pattern of z-average radius of gyration as well as particle size change was similar to that of Mw, and z-average radius of gyration decreased much more slowly, especially for high-DS OSA starch. Compared to native starch, two characteristic absorption peaks at 1726.76 and 1571.83 cm(-1) were observed in FT-IR spectra, and the intensity of absorption peaks increased with increasing DS. The NMR results showed that OSA starch had several additional peaks at 0.8-3.0 ppm and a shoulder at 5.56 ppm for OSA substituents, which were grafted at O-2 and O-3 positions in soluble starch. The even distribution of OSA groups in the center area of soluble starch particle has been directly shown under CLSM. Most substitutions were located near branching points of soluble starch particles for a low-DS modified starch, whereas the substituted ester groups were located near branching points as well as at the nonreducing ends in OSA starch with a high DS.

  6. Trimellitic anhydride-conjugated serum albumin activates rat alveolar macrophages in vitro

    Directory of Open Access Journals (Sweden)

    Bloksma Nanne

    2006-06-01

    Full Text Available Abstract Background Occupational exposure to airborne low molecular weight chemicals, like trimellitic anhydride (TMA, can result in occupational asthma. Alveolar macrophages (AMs are among the first cells to encounter these inhaled compounds and were previously shown to influence TMA-induced asthma-like symptoms in the Brown Norway rat. TMA is a hapten that will bind to endogenous proteins upon entrance of the body. Therefore, in the present study we determined if TMA and TMA conjugated to serum albumin induced the production of the macrophage mediators nitric oxide (NO, tumour necrosis factor (TNF, and interleukin 6 (IL-6 in vitro using the rat AM cell line NR8383 and primary AMs derived from TMA-sensitized and naïve Brown Norway rats. Methods Cells were incubated with different concentrations of TMA, TMA conjugated to bovine serum albumin (BSA, and BSA as a control for 24 h and the culture supernatant was analyzed for mediator content. Results TMA alone was not able to induce the production of mediators by NR8383 cells and primary AMs from sensitized and sham-treated rats. TMA-BSA, on the contrary, dose-dependently stimulated the production of NO, TNF, and IL-6 by NR8383 cells and of NO and TNF, but not IL-6, by primary AMs independent of sensitization. Conclusion Results suggest that although TMA is a highly reactive compound, conjugation to a suitable protein is necessary to induce mediator production by AMs. Furthermore, the observation that effects of TMA-BSA were independent of sensitization suggests involvement of an immunologically non-specific receptor. In the discussion it is argued that a macrophage scavenger receptor is a likely candidate.

  7. Evaporative Derivatization of Phenols with 2-Sulfobenzoic Anhydride for Detection by MALDI-MS

    Science.gov (United States)

    Yao, Yuanyuan; Wang, Poguang; Giese, Roger

    2014-01-01

    RATIONALE Phenols are an important class of analytes, for example as bioactive environmental contaminants. Towards a goal of improving their detection by MALDI-TOF-MS or MALDI-TOF/TOF-MS, we studied their derivatization with 2-sulfobenzoic anhydride (SBA). We chose SBA for this purpose since it is commercially available, inexpensive, and forms an anionic derivative. METHODS In selected conditions developed here for phenols, a reaction mixture of one or more of such compounds in acetonitrile containing SBA and 4-dimethylaminopyridine (DMAP) is evaporated to a solid, heated at 60°C for 1 h, redissolved in 50% acetonitrile containing matrix, spotted onto a MALDI target, and subjected to negative ion MALDI-TOF/TOF-MS. RESULTS While conventional (solution-phase) reaction of 4-phenylphenol (model analyte) with SBA and DMAP only gave a 47% yield of SBA-tagged 4-phenylphenol, evaporative derivatization as above gave a 96% yield, and 25 pmol (4.3 ng) of 4-phenylphenol could be detected in this way by MALDI-TOF/TOF-MS at S/N = 260, whereas even 1 nmol of the nonderivatized phenol was not detected in the absence of derivatization. A wide range of responses was observed when a mixture of 15 phenols was derivatized, with the higher responses coming from phenols with a pKa value above 9. Without derivatization, phenols with pKa values below 5 were the most readily detected. CONCLUSION Evaporative derivatization with SBA (a convenient reagent) can improve the detection of phenols with relatively high pKa values (above 9) by negative ion MALDI-TOF-MS, and accomplish this in the absence of post-derivatization reaction cleanup. PMID:24519828

  8. Structural properties of pepsin-solubilized collagen acylated by lauroyl chloride along with succinic anhydride

    Energy Technology Data Exchange (ETDEWEB)

    Li, Conghu [The Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065 (China); College of Life Sciences, Anqing Normal University, Anqing 246011 (China); Tian, Zhenhua; Liu, Wentao [The Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065 (China); Li, Guoying, E-mail: liguoyings@163.com [The Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065 (China)

    2015-10-01

    The structural properties of pepsin-solubilized calf skin collagen acylated by lauroyl chloride along with succinic anhydride were investigated in this paper. Compared with native collagen, acylated collagen retained the unique triple helix conformation, as determined by amino acid analysis, circular dichroism and X-ray diffraction. Meanwhile, the thermostability of acylated collagen using thermogravimetric measurements was enhanced as the residual weight increased by 5%. With the temperature increased from 25 to 115 °C, the secondary structure of native and acylated collagens using Fourier transform infrared spectroscopy measurements was destroyed since the intensity of the major amide bands decreased and the positions of the major amide bands shifted to lower wavenumber, respectively. Meanwhile, two-dimensional correlation spectroscopy revealed that the most sensitive bands for acylated and native collagens were amide I and II bands, respectively. Additionally, the corresponding order of the groups between native and acylated collagens was different and the correlation degree for acylated collagen was weaker than that of native collagen, suggesting that temperature played a small influence on the conformation of acylated collagen, which might be concluded that the hydrophobic interaction improved the thermostability of collagen. - Highlights: • Acylated collagen retained the unique triple helix conformation. • Acylated collagen had stronger thermostability than native collagen. • Amide I was the most sensitive band to the temperature for acylated collagen. • Amide II was the most sensitive band to the temperature for native collagen. • Auto-peak at 1680 cm{sup −1} for acylated collagen disappeared at higher temperature.

  9. Cure mechanisms in materials for use in esthetic dentistry.

    Science.gov (United States)

    Kwon, Tae-Yub; Bagheri, Rafat; Kim, Young K; Kim, Kyo-Han; Burrow, Michael F

    2012-02-01

    The current paper reviews the curing mechanisms found in resin-based materials used in dentistry. Historical aspects of dental products and the associated curing mechanisms are reviewed. In comparison with common industrial procedures, curing methods employed for dental materials are relatively limited because of the need to polymerize quickly in the oral cavity at an ambient temperature. Heat-cure and self-cure dental resins utilize benzoyl peroxide initiator alone with a tertiary amine co-initiator. At present, most dental restorative composites use a camphorquinone-amine complex initiation, visible light-cure, one-component systems, although alternative photoinitiators have been researched and developed. A multiple curing mode in a dual-cure material is a complex combination of various initiation systems. The use of aryl sulfinic acid sodium salt to overcome adverse chemical interactions between simplified adhesives and self- or dual-cure composites is based on another self-cure polymerization mechanism, sulfinic acid-initiated polymerization, proposed by Hagger in 1948. The sodium salt of aryl sulfinic acid reacts with an acidic monomer in simplified adhesives, and is believed to produce radicals. Clinically, it is important to try to optimize the degree of conversion of resin-based materials using proper manipulation and adequate light-curing techniques to ensure the best outcome for materials used to restore teeth.

  10. Rubber curing chemistry governing the orientation of layered silicate

    Directory of Open Access Journals (Sweden)

    2007-11-01

    Full Text Available The effect of curing systems on the orientation and the dispersion of the layered silicates in acrylonitrile butadiene rubber nanocomposite is reported. Significant differences in X-ray diffraction pattern between peroxide curing and sulfur curing was observed. Intense X-ray scattering values in the XRD experiments from peroxide cured vulcanizates indicate an orientation of the layers in a preferred direction as evinced by transmission electron micrographs. However, sulfur cured vulcanizates show no preferential orientation of the silicate particles. Nevertheless, a closer inspection of transmission electron microscopy (TEM images of peroxide and sulfur cured samples shows exfoliated silicate layers in the acrylonitrile butadiene rubber (NBR matrix. It was revealed in the prevailing study that the use of an excess amount of stearic acid in the formulation of the sulfur curing package leads to almost exfoliated type X-ray scattering pattern.

  11. Cure shrinkage effects in epoxy and polycyanate matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Spellman, G.P.

    1995-12-22

    A relatively new advanced composite matrix, polycyanate ester, was evaluated for cure shrinkage. The chemical cure shrinkage of composites is difficult to model but a number of clever experimental techniques are available to the investigator. In this work the method of curing a prepreg layup on top of a previously cured laminate of identical ply composition is utilized. The polymeric matrices used in advanced composites have been primarily epoxies and therefore a common system of this type, Fiberite 3501-6, was used as a base case material. Three polycyanate matrix systems were selected for the study. These are: Fiberite 954-2A, YLA RS-3, and Bryte Technology BTCy-1. The first three of these systems were unidirectional prepreg with carbon fiber reinforcement. The Bryte Technology material was reinforced with E-glass fabric. The technique used to evaluate cure shrinkage results in distortion of the flatness of an otherwise symmetric laminate. The first laminate is cured in a conventional fashion. An identical layup is cured on this first laminate. During the second cure all constituents are exposed to the same thermal cycles. However, only the new portion of the laminate will experience volumetric changes associate with matrix cure. The additional strain of cure shrinkage results in an unsymmetric distribution of residual stresses and an associated warpage of the laminate. The baseline material, Fiberite 3501-6, exhibited cure shrinkage that was in accordance with expectations. Cure strains were {minus}4.5E-04. The YLA RS-3 material had cure strains somewhat lower at {minus}3.2E-04. The Fiberite 954-2A cure strain was {minus}1.5E-04 that is 70% lower than the baseline material. The glass fabric material with the Bryte BTCy-1 matrix did not result in meaningful results because the processing methods were not fully compatible with the material.

  12. Experimental Study on the Curing Effect of Dredged Sediments with Three Types of Curing Agents

    Directory of Open Access Journals (Sweden)

    Yan Lei-Ming

    2016-01-01

    Full Text Available Sediment solidification technology is widely used to dispose dredged sediment, three types of curing agents were used in this study to solidified the dredged sediment from shallows in Nantong with three types of curing agents: JY, ZL and FJ. The results showed that the optimal additive amounts of these three curing agents were 140g JY, 16g ZL, 2.0g FJ per 1000g of the dredged sediment respectively, their 28d USC were up to 2.48 MPa, 2.96 MPa and 3.00 MPa. JY has obvious early strength effect, which of FJ is not that obvious, but the later-stage strength of sediment solidified by FJ are relatively higher.

  13. CURING KINETICS AND PROPERTIES OF ACRYLIC RESIN CURED WITH AZIRIDINE CROSSLINKER

    Institute of Scientific and Technical Information of China (English)

    Fei Xie; Zong-hui Liu; De-qing Wei

    2002-01-01

    A kind of aziridine crosslinkers was synthesized and used to crosslink acrylate copolymers. The crosslinking properties and curing kinetics of the resin were studied. It was found that with the increase of the content of crosslinker in the emulsion, the mechanical properties and solvent resistance of the resin will be apparently improved, but its glass transition temperature (Tg) is very low. The lowest amount of crosslinker used in the acrylic resin emulsion is 0.25%. Curing kinetics studied by DSC show that this curing reaction occurs readily because the apparent activation energy of the reaction is low(65.1 KJ/mol). These results demonstrate that the aziridine crosslinker is indeed a low temperature crosslinking agent and can be used at room temperature.

  14. A New Process for Maleic Anhydride Synthesis from a Renewable Building Block: The Gas-Phase Oxidehydration of Bio-1-butanol.

    Science.gov (United States)

    Pavarelli, Giulia; Velasquez Ochoa, Juliana; Caldarelli, Aurora; Puzzo, Francesco; Cavani, Fabrizio; Dubois, Jean-Luc

    2015-07-01

    We investigated the synthesis of maleic anhydride by oxidehydration of a bio-alcohol, 1-butanol, as a possible alternative to the classical process of n-butane oxidation. A vanadyl pyrophosphate catalyst was used to explore the one-pot reaction, which involved two sequential steps: 1) 1-butanol dehydration to 1-butene, catalysed by acid sites, and 2) the oxidation of butenes to maleic anhydride, catalysed by redox sites. A non-negligible amount of phthalic anhydride was also formed. The effect of different experimental parameters was investigated with chemically sourced 1-butanol, and the results were then confirmed by using genuinely bio-sourced 1-butanol. In the case of bio-1-butanol, however, the purity of the product remarkably affected the yield of maleic anhydride. It was found that the reaction mechanism includes the oxidation of butenes to crotonaldehyde and the oxidation of the latter to either furan or maleic acid, both of which are transformed to produce maleic anhydride.

  15. An Examination of the Chemistry of Peroxycarboxylic Nitric Anhydrides and Related Volatile Organic Compounds During Texas Air Quality Study 2000 Using Ground-Based Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, James M.; Jobson, B Tom T.; Kuster, W. C.; Goldan, P. D.; Murphy, Paul; Williams, Eric; Frost, G. J.; Riemer, D.; Apel, Eric; Stroud, C.; Wiedinmyer, Christine; Fehsenfeld, Fred C.

    2003-08-19

    Measurements of peroxycarboxylic nitric anhydrides (PANs) along with related volatile organic compounds (VOCs) were made at the La Porte super site during the TexAQS 2000 Houston study. The PAN mixing ratios ranged up to 6.5 ppbv and were broadly correlated with O3, characteristic of a highly polluted urban environment. The anthropogenic PAN homologue concentrations were generally consistent with those found in other urban environments; peroxypropionic nitric anhydride (PPN) averaged 15%, and peroxyisobutyric nitric anhydride (PiBN) averaged 3% of PAN,. Some periods were noted where local petrochemical sources resulted in anomalous PANs chemistry. This effect was especially noticeable in the case of peroxyacrylic nitric anhydride (APAN) where local sources of 1,3-butadiene and acrolein resulted in APAN as high as 30% of PAN. Peroxymethacrylic nitric anhydride (MPAN) was a fairly minor constituent of the PANs except for two periods on 4 and 5 September when air masses from high biogenic hydrocarbons (BHC) areas were observed. BHC chemistry was not a factor in the highest ozone pollution episodes in Houston but may have an impact on daily average ozone levels in some circumstances.

  16. Biocompatible photocrosslinked poly(ester anhydride) based on functionalized poly(epsilon-caprolactone) prepolymer shows surface erosion controlled drug release in vitro and in vivo.

    Science.gov (United States)

    Mönkäre, J; Hakala, R A; Vlasova, M A; Huotari, A; Kilpeläinen, M; Kiviniemi, A; Meretoja, V; Herzig, K H; Korhonen, H; Seppälä, J V; Järvinen, K

    2010-09-15

    Star-shaped poly(epsilon-caprolactone) oligomers functionalized with succinic anhydride were used as prepolymers to prepare photocrosslinked poly(ester anhydride) to evaluate their in vivo drug delivery functionality and biocompatibility. Thus, in this work, erosion, drug release and safety of the photocrosslinked poly(ester anhydride) were examined in vitro and in vivo. A small water-soluble drug, propranolol HCl (M(w) 296 g/mol, solubility 50 mg/ml), was used as the model drug in an evaluation of the erosion controlled release. Drug-free and drug-loaded (10-60% w/w) poly(ester anhydride) discoids eroded in vitro (pH 7.4 buffer, +37 degrees C) linearly within 24-48 h. A strong correlation between the polymer erosion and the linear drug release in vitro was observed, indicating that the release had been controlled by the erosion of the polymer. Similarly, in vivo studies (s.c. implantation of discoids in rats) indicated that surface erosion controlled drug release from the discoids (drug loading 40% w/w). Oligomers did not decrease cell viability in vitro and the implanted discoids (s.c., rats) did not evoke any cytokine activity in vivo. In summary, surface erosion controlled drug release and the safety of photocrosslinked poly(ester anhydride) were demonstrated in this study.

  17. Improving a self-curing dental resin by eliminating oxygen, hydroquinone and water from its curing process.

    Science.gov (United States)

    Keh, En-Sheng; Hayakawa, Iwao; Takahashi, Hidekazu; Watanabe, Akihiko; Iwasaki, Yasuhiko; Akiyoshi, Kazunari; Nakabayashi, Nobuo

    2002-12-01

    Self-curing dental resins are always manipulated in the presence of curing inhibitory factors such as oxygen, hydroquinone, water and another contaminants such as saliva and blood. The purpose of this study was to elucidate the effects of eliminating these curing inhibitory factors on resin properties. Several clinically relevant characteristics of an experimental resin cured in the absence of inhibitory factors (purified group) were determined and compared with the resin cured conventionally (control group). The purified group showed a significantly shorter induction period and higher reaction exotherm. It also showed significantly higher tensile strength and lower strain to failure. With regard to the amount of residual monomer, fracture toughness and fatigue strength the improvements were not significant. These findings suggest that the polymerization outcomes and mechanical properties of the purified group resin can be improved in general. Dental clinicians should pay attention to the storage and curing environments while manipulating the self-curing resin.

  18. Samarium-modified vanadium phosphate catalyst for the selective oxidation of n-butane to maleic anhydride

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Hua-Yi [State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of Alcohols, Ethers and Esters, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Wang, Hai-Bo [Fushun Res InstPetr& Petrochem, Fushun, 113001 (China); Liu, Xin-Hua; Li, Jian-Hui; Yang, Mei-Hua [State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of Alcohols, Ethers and Esters, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Huang, Chuan-Jing, E-mail: huangcj@xmu.edu.cn [State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of Alcohols, Ethers and Esters, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Weng, Wei-Zheng [State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of Alcohols, Ethers and Esters, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Wan, Hui-Lin, E-mail: hlwan@xmu.edu.cn [State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of Alcohols, Ethers and Esters, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China)

    2015-10-01

    Graphical abstract: The addition of a small amount of Sm into VPO catalyst brought about great changes in its physicochemical properties such as surface area, surface morphology, phase composition and redox property, thus leading to a higher catalytic performance in the selective oxidation of n-butane to maleic anhydride, as compared to the undoped VPO catalyst. - Highlights: • The addition of Sm leads to great changes in the structure of VPO catalyst. • Sm improves performance of VPO for oxidation of n-butane to maleic anhydride. • Catalytic performance is closely related to structure of VPO catalyst. - Abstract: A series of samarium-modified vanadium phosphate catalysts were prepared and studied in selective oxidation of n-butane to maleic anhydride. The catalytic evaluation showed that Sm modification significantly increased the overall n-butane conversion and intrinsic activity. N{sub 2}-adsorption, XRD, SEM, Raman, XPS, EPR and H{sub 2}-TPR techniques were used to investigate the intrinsic difference among these catalysts. The results revealed that the addition of Sm to VPO catalyst can increase the surface area of the catalyst, lead to a significant change in catalyst morphology from plate-like structure into rosette-shape clusters, and largely promote the formation of (VO){sub 2}P{sub 2}O{sub 7}. All of these were related to the different catalytic performance of Sm-doped and undoped VPO catalysts. The roles of the different VOPO{sub 4} phases and the influence of Sm were also described and discussed.

  19. 架空导线用碳纤维复合芯固化剂应用研究%Application of Curing Agent in Carbon Fiber Composite Core For Overhead Transmission Lines

    Institute of Scientific and Technical Information of China (English)

    何州文; 陈新; 药宁娜; 杨长龙; 陈懿夫

    2012-01-01

    A compound curing agent was prepared with methyl tetrahydrophthalic anhydride curing agent and a kind of flexible curing agent by a certain percentage for carbon fiber composite core epoxy matrix toughening. The structure of curing agent was studied by means of FTIR. The effects of the compound curing agent on impact strength, winding performance, apparent shear strength and temperature resistance of the carbon fiber composite core were investigated. The results showed that the flexible curing agent contained long-chain flexible segments, which could improve the impact strength, winding performance and apparent shear strength and had less effect on the temperature resistance for the carbon fiber composite core.%将甲基四氢苯酐固化剂与柔性固化剂按一定比例复配,用于碳纤维复合芯环氧树脂基体的增韧改性.采用傅里叶变换红外光谱分析固化剂的结构;研究了固化剂对碳纤维复合芯冲击强度、卷绕性能、剪切强度及耐温性的影响.结果表明,柔性固化剂含有长链结构的柔性链段,提高了碳纤维复合芯冲击强度、卷绕性能及表观剪切强度,并且对碳纤维复合芯的耐温性影响较小.

  20. Short-chain grafting of tetrahydrofuran and 1,4-dioxane cycles on vinylchloride-maleic anhydride copolymer

    Directory of Open Access Journals (Sweden)

    2009-01-01

    Full Text Available Mass increase of vinylchloride-maleic anhydride (VC-MA copolymer samples aged in tetrahydrofuran (THF or in 1,4-dioxane results from chemical interaction of VC-MA macromolecules with 1,4-dioxane or THF. Microstructure of the products of such modification was proved by infrared spectroscopy (IR- and nuclear magnetic resonance spectroscopy (13C NMR and 1H NMR. Mechanism of modification has been proposed. The results of microstructure research of VC-MA samples aged in THF and in 1,4-dioxane coincide with already known data on the reactions of opening of these and other oxygen-containing cycles under mild conditions.

  1. KINETIC STUDY OF CARBONYLATION OF METHANOL TO ACETIC ACID AND ACETIC ANHYDRIDE OVER A NOVEL COPOLYMER- BOUND CIS- DICARBONYLRHODIUM COMPLEX

    Institute of Scientific and Technical Information of China (English)

    CHEN Yuying; YUAN Guoqing; CHEN Rongyao

    1989-01-01

    The kinetic study of carbonylation of methanol-acetic acid mixture to acetic acid and acetic anhydride over a cis-dicarbonylrhodium complex (MVM' Rh)coordinated with the ethylene diacrylate (M')crosslinked copolymer of methyl acrylate (M) and 2 - vinylpyridine (V) shows that the rate of reaction is zero order with respect to both reactants methanol and carbon monoxide, but first order in the concentrations of promoter methyl iodide and rhodium in the complex . Polar solvents can accelerate the reaction .Activation parameters were calculated from the experimental results, being comparable to that of the homogeneous system . A mechanism similar to that of soluble rhodium catalyst was proposed .

  2. SELECTIVE SEPARATION OF WATER—ETHANOL MIXTURE THROUGH COPOLYMERIC MEMBRANES.Ⅱ.ACRYLONITRILE AND MALEIC ANHYDRIDE COPOLYMERIC MEMBRANES

    Institute of Scientific and Technical Information of China (English)

    ZHangFuyao; ZhangYifeng; 等

    1993-01-01

    Acrylonitrile(AN) and maleic anhydride(MA) copolymer has been synthesized by radical polymerization using ammonium persulfate and sodium bisulfite as initiator.The pervaporation properties of the copolymeric membranes prepared have been investigated for the first time. The dependences of pervaporation characteristics on coplymer composition,feed concentration and operating temperature have been studied.In order to improve the separation properties of the copolymeric membranes,the membranes were hydrolyzed with 10 wt% soldium hydroxide or potassium hydroxide aqueous solution.The hydrolyzed membranes containing more than 0.069MA mol fraction showed higher tensile strength and separation properties than the original membranes.

  3. SYNTHESIS AND CHARACTERIZATION OF A NEW COMBLIKE POLYMER BASED ON POLY (VINYL METHYL ETHER-ALT-MALEIC ANHYDRIDE) BACKBONE

    Institute of Scientific and Technical Information of China (English)

    DING Liming; LIN Yunqing; ZHOU Zinan; NI Jianlong; CHEN Donglin

    1995-01-01

    A new comblike polymer host for polymer electrolyte was synthesized by reacting monomethyl ether of poly(ethylene glycol) with poly(vinyl methyl ether-alt-maleic anhydride) and endcapping the residual carboxylic acid with methanol. Butanone was selected as a solvent for the esterification in order to obtain a completely soluble product. The synthesis process was traced through by IR. Compared with the model compounds, the presumed structure of this comblike polymer has been proved to be valid by 13C NMR. The comb polymer is a white rubbery solid. It can be dissolved in butanone and THF, and manifests good film forming ability.

  4. Mechanical modeling of stress generation during cure of encapsulating resins

    Energy Technology Data Exchange (ETDEWEB)

    Lagasse, R.R.; Chambers, R.S.; Guess, T.R. (Sandia National Labs., Albuquerque, NM (USA)); Plazek, D.J.; Bero, C. (Pittsburgh Univ., PA (USA). Dept. of Materials Science and Engineering)

    1991-01-01

    We have developed a numerical model for calculating stresses generated during cure of shrinking encapsulating resins. Mechanical modeling of polymer encapsulated electronic devices usually focuses on stress generated during cooling after cure. The stress developed during cure, due to shrinkage of the encapsulant, is normally neglected. That assumption is valid if both the shear and bulk moduli of the encapsulant at the cure temperature are negligible with respect to the moduli at lower temperatures. Our measurements on a model epoxy encapsulant show that the shear modulus during cure, varying from 0 to 6 MPa, is at least 100 times smaller than that at ambient temperature. In contrast, the bulk modulus at the cure temperature is only 2.5 times smaller. Since the bulk modulus during cure cannot be neglected, significant stress can be produced if volume shrinkage is constrained by a stiff mold or embedded elements. In fact, mechanical failure of encapsulating materials during cure has been evident in some of our experiments. Using measurements of shear and bulk moduli plus volume shrinkage as inputs to a finite element model, we have successfully predicted the shrinkage strains and stresses developed during cure of a model epoxy resin inside a cylindrical tube. Consideration of cure shrinkage stress has led to a process modification that appears to reduce mechanical failures in a real encapsulated device. 6 refs., 6 figs.

  5. Critical parameters for electron beam curing of cationic epoxies and property comparison of electron beam cured cationic epoxies versus thermal cured resins and composites

    Energy Technology Data Exchange (ETDEWEB)

    Janke, C.J.; Norris, R.E.; Yarborough, K. [Oak Ridge National Lab., TN (United States). Oak Ridge Centers for Manufacturing Technology; Havens, S.J. [Oak Ridge Inst. for Science and Education, TN (United States); Lopata, V.J. [Atomic Energy of Canada Ltd., Pinawa, Manitoba (Canada). Whiteshell Labs.

    1997-01-16

    Electron beam curing of composites is a nonthermal, nonautoclave curing process offering the following advantages compared to conventional thermal curing: substantially reduced manufacturing costs and curing times; improvements in part quality and performance; reduced environmental and health concerns; and improvements in material handling. In 1994 a Cooperative Research and Development Agreement (CRADA), sponsored by the Department of Energy Defense Programs and 10 industrial partners, was established to advance electron beam curing of composites. The CRADA has successfully developed hundreds of new toughened and untoughened resins, offering unlimited formulation and processing flexibility. Several patent applications have been filed for this work. Composites made from these easily processable, low shrinkage material match the performance of thermal cured composites and exhibit: low void contents comparable to autoclave cured composites (less than 1%); superb low water absorption values in the same range as cyanate esters (less than 1%); glass transition temperatures rivaling those of polyimides (greater than 390 C); mechanical properties comparable to high performance, autoclave cured composites; and excellent property retention after cryogenic and thermal cycling. These materials have been used to manufacture many composite parts using various fabrication processes including hand lay-up, tow placement, filament winding, resin transfer molding and vacuum assisted resin transfer molding.

  6. Synthesis of comb-like copolymers from renewable resources: Itaconic anhydride, stearyl methacrylate and lactic acid

    Science.gov (United States)

    Shang, Shurui

    The synthesis and properties of comb-like copolymers and ionomers derived from renewable resources: itaconic anhydride (ITA), stearyl methacrylate (SM) and lactic acid (LA) are described. The copolymers based on ITA and SM (ITA-SM) were nearly random with a slight alternating tendency. The copolymers exhibited a nanophase-separated morphology, with the stearate side-chains forming a bilayer, semi-crystalline structure. The crystalline side-chains suppressed molecular motion of the main-chain, so that a glass transition temperature (Tg) was not resolved unless the ITA concentration was sufficiently high so that Tg > the melting point (Tm). The softening point and modulus of the copolymers increased with the increasing ITA concentration, but the thermal stability decreased. The ITA moiety along the main chain of the copolymers was neutralized with metal acetates to produce Na-, Ca- and Zn- random ionomers with comb-like architectures. In general, the incorporation of the ionic groups increased the Tg and suppressed the crystallinity of the side-chain packing. Ionomers with high SM side-chain density had two competing driving forces for self-assembled nano-phase separation: ionic aggregation and side-chain crystalline packing. Upon neutralization, a morphological transition from semi-crystalline lamella to spherical ionic aggregation was observed by small angle X-ray scattering (SAXS) analysis and transmission electron microscopy (TEM). Thermomechanical analysis revealed an increasing resistance to penetration deformation with an increasing degree of neutralization and an apparent rubbery plateau was observed above Tg. A controlled transesterification of PLA in glassware was an effective way to prepare a methacrylate functionalized PLA macromonomer with controlled molecular weight, which was used to synthesize a variety of copolymers. The copolymerization of this functionalized PLA macromonomer with ITA totally suppressed the side-chain crystallinity for the PLA chain

  7. Influence of curing protocol on selected properties of light-curing polymers

    DEFF Research Database (Denmark)

    Dewaele, Magali; Asmussen, Erik; Peutzfeldt, Anne;

    2009-01-01

    The purpose of this study was to investigate the effect of light-curing protocol on degree of conversion (DC), volume contraction (C), elastic modulus (E), and glass transition temperature (T(g)) as measured on a model polymer. It was a further aim to correlate the measured values with each other....

  8. Investigation of the ageing effects on phenol-urea-formaldehyde binder and alkanol amine-acid anhydride binder coated mineral fibres

    DEFF Research Database (Denmark)

    Zafar, Ashar; Schjødt-Thomsen, Jan; Sodhi, R.;

    2013-01-01

    Phenol-Urea-Formaldehyde (PUF) binder coated mineral fibres' mechanical properties have been observed to degrade during ageing at elevated temperatures and humidity, while alkanol amine-acid anhydride binder based mineral fibres exhibited better ageing properties for same duration of ageing. X......-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were employed to identify the chemical changes occurring in the PUF binder coated mineral fibres and alkanol amine-acid anhydride binder coated mineral fibres during that ageing. The samples were aged in a climate...... of amide, methylene ether and methylene linkages between urea groups present in the PUF binder. In the case of the alkanol amine-acid anhydride binder coated mineral fibres, both XPS and ToF-SIMS techniques consistently showed that the surface chemical composition of the organic components of the alkanol...

  9. 琥珀酸酐生产新工艺探讨%The Study of New Technology of Producing Amber Anhydride

    Institute of Scientific and Technical Information of China (English)

    吕杨

    2012-01-01

    It introduced the properties of Amber Anhydride and widely used in every field.Introducing the major technology of producing Amber Anhydride.Reviewing new tecnology of producing Amber Anhydride and comparing the major technology with new technology to explaining the superiority of new technology.%介绍了琥珀酸酐的性质及在各个领域的广泛用途,介绍了目前国内琥珀酸酐的主要生产工艺技术方案,综述了琥珀酸酐生产新技术,并对目前国内琥珀酸酐的主要生产工艺和琥珀酸酐生产新工艺进行了比较,突出了新工艺的优势。

  10. Out-of-Autoclave Cure Composites

    Science.gov (United States)

    Hayes, Brian S.

    2015-01-01

    As the size of aerospace composite parts exceeds that of even the largest autoclaves, the development of new out-of-autoclave processes and materials is necessary to ensure quality and performance. Many out-of-autoclave prepreg systems can produce high-quality composites initially; however, due to long layup times, the resin advancement commonly causes high void content and variations in fiber volume. Applied Poleramic, Inc. (API), developed an aerospace-grade benzoxazine matrix composite prepreg material that offers more than a year out-time at ambient conditions and provides exceptionally low void content when out-of-autoclave cured. When compared with aerospace epoxy prepreg systems, API's innovation offers significant improvements in terms of out-time at ambient temperature and the corresponding tack retention. The carbon fiber composites developed with the optimized matrix technology have significantly better mechanical performance in terms of hot-wet retention and compression when compared with aerospace epoxy matrices. These composites also offer an excellent overall balance of properties. This matrix system imparts very low cure shrinkage, low coefficient of thermal expansion, and low density when compared with most aerospace epoxy prepreg materials.

  11. CURE: Clean use of reactor energy

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1990-05-01

    This paper presents the results of a joint Westinghouse Hanford Company (Westinghouse Hanford)-Pacific Northwest Laboratory (PNL) study that considered the feasibility of treating radioactive waste before disposal to reduce the inventory of long-lived radionuclides, making the waste more suitable for geologic disposal. The treatment considered here is one in which waste would be chemically separated so that long-lived radionuclides can be treated using specific processes appropriate for the nuclide. The technical feasibility of enhancing repository performance by this type of treatment is considered in this report. A joint Westinghouse Hanford-PNL study group developed a concept called the Clean Use of Reactor Energy (CURE), and evaluated the potential of current technology to reduce the long-lived radionuclide content in waste from the nuclear power industry. The CURE process consists of three components: chemical separation of elements that have significant quantities of long-lived radioisotopes in the waste, exposure in a neutron flux to transmute the radioisotopes to stable nuclides, and packaging of radionuclides that cannot be transmuted easily for storage or geologic disposal. 76 refs., 32 figs., 24 tabs.

  12. In situ cure monitoring of advanced fiber reinforced composites

    Science.gov (United States)

    Powell, Graham R.; Crosby, Peter A.; Fernando, Gerard F.; France, Chris M.; Spooncer, Ronald C.; Waters, David N.

    1995-04-01

    This paper describes a comparative study of in-situ cure monitoring and cure modelling by three methods: (a) evanescent wave spectroscopy, (b) refractive index change, (c) near- infrared spectroscopy. Optical fibers were embedded into aerospace epoxy resins during the manufacturing process of the composite. The cure characteristics were then tracked in real- time during the processing of the material via evanescent wave interaction. This technique is based upon monitoring of characteristic infrared absorption bands of the resin system to find the concentration of the epoxy and amine hardener as a function of cure time. Hence this technique is suitable for on-line process monitoring and optimization. Results obtained from the optical fiber sensors were used to model the curing behavior of the resin system. The results were compared with near-infrared spectroscopy and differential scanning calorimetry experiments carried out under similar conditions. The feasibility of utilizing refractive index changes to monitor the extent of cure has also been demonstrated.

  13. Photoacoustic monitoring of inhomogeneous curing processes in polystyrene emulsions

    Energy Technology Data Exchange (ETDEWEB)

    Vargas-Luna, M.; Gutierrez-Juarez, G.; Rodriguez-Vizcaino, J.M.; Varela-Nsjera, J.B.; Rodriguez-Palencia, J.M.; Bernal-Alvarado, J.; Sosa, M. [Instituto de Fisica, Universidad de Guanajuato, Leon, Guanajuato (Mexico); Alvarado-Gil, J.J. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Merida, Antigua Carretera a Progreso, Merida, Yucatan (Mexico)

    2002-07-07

    The time evolution of the inhomogeneous curing process of polystyrene emulsions is studied using a variant of the conventional photoacoustic (PA) technique. The thermal effusivity, as a function of time, is determined in order to monitor the sintering process of a styrene emulsion in different steps of the manufacturing procedure. PA measurements of thermal effusivity show a sigmoidal growth as a function of time during the curing process. The parameterization of these curves permits the determination of the characteristic curing time and velocity of the process. A decreasing of the curing time and an increasing curing velocity for the final steps of the manufacturing process are observed. The feasibility of our approach and its potentiality for the characterization of other curing process are discussed. (author)

  14. Amphiphilic graft copolymer based on poly(styrene-co-maleic anhydride with low molecular weight polyethylenimine for efficient gene delivery

    Directory of Open Access Journals (Sweden)

    Duan XP

    2012-09-01

    Full Text Available Xiaopin Duan,1,2 Jisheng Xiao,2 Qi Yin,2 Zhiwen Zhang,2 Shirui Mao,1 Yaping Li21School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, 2Center of Pharmaceutics, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, ChinaBackground and methods: A new amphiphilic comb-shaped copolymer (SP was synthesized by conjugating poly(styrene-co-maleic anhydride with low molecular weight polyethyleneimine for gene delivery. Fourier transform infrared spectrum, 1H nuclear magnetic resonance, and gel permeation chromatography were used to characterize the graft copolymer.Results: The buffering capability of SP was similar to that of polyethyleneimine within the endosomal pH range. The copolymer could condense DNA effectively to form complexes with a positive charge (13–30 mV and a small particle size (130–200 nm at N/P ratios between 5 and 20, and protect DNA from degradation by DNase I. In addition, SP showed much lower cytotoxicity than polyethyleneimine 25,000. Importantly, the gene transfection activity and cellular uptake of SP-DNA complexes were all markedly higher than that of complexes of polyethyleneimine 25,000 and DNA in MCF-7 and MCF-7/ADR cell lines.Conclusion: This work highlights the promise of SP as a safe and efficient synthetic vector for DNA delivery.Keywords: poly(styrene-co-maleic anhydride, polyethylenimine, DNA, gene delivery

  15. Controlled Release of Damascone from Poly(styrene-co-maleic anhydride-based Bioconjugates in Functional Perfumery

    Directory of Open Access Journals (Sweden)

    Andreas Herrmann

    2013-02-01

    Full Text Available Poly(styrene-co-maleic anhydrides were modified with poly(propylene oxide (PO-co-ethylene oxide (EO side chains (Jeffamine® with different EO/PO molar ratios, varying between 0.11 and 3.60. These copolymers were then further functionalized with a β-mercapto ketone of δ-damascone. The obtained poly(maleic acid monoamide-based β-mercapto ketones were then studied as delivery systems for the controlled release of δ-damascone by retro 1,4-addition. The release of δ-damascone, a volatile, bioactive molecule of the family of rose ketones, was studied by dynamic headspace analysis above a cotton surface after deposition of a cationic surfactant containing fabric softening formulation, as a function of the ethylene oxide (EO/propylene oxide (PO molar ratio of the grafted copolymer side chains. The polarity of the EO/PO side chain influenced the release efficiency of the damascone in a typical fabric softening application. PO-rich copolymers and the corresponding poly(styrene-co-maleic anhydride without Jeffamine® side chains were found to be less efficient for the desired fragrance release than the corresponding bioconjugate with a EO/PO ratio of 3.60 in the side chain. This copolymer conjugate seemed to represent a suitable balance between hydrophilicity and hydrophobicity to favor the release of the δ-damascone and to improve the deposition of the conjugate from an aqueous environment onto a cotton surface.

  16. Development of novel melt-compounded starch-grafted polypropylene/polypropylene-grafted maleic anhydride/organoclay ternary hybrids

    Directory of Open Access Journals (Sweden)

    E. Lafranche

    2012-11-01

    Full Text Available Starch-grafted polypropylene (PP-g-starch/organoclay nanocomposites were melt-compounded using a corotating twin-screw extruder. Homopolymer or copolymer-based polypropylene-grafted maleic anhydrides (PP-g-MA with different molecular weights and different maleic anhydride (MA grafting levels were added at different weight contents as compatibilizer. Two organo-modified montmorillonites were used, the first one containing polar functional groups (Cloisite®30B having affinity to the starch phase, and the other one containing non polar-groups (Cloisite®20A having affinity to the polypropylene phase of the polymer matrix. Whatever the MA grafting level and the molecular weight and content of PP-g-MA, no significant immiscibility of PP-g-starch/PP-g-MA blends is evidenced. Regarding clay dispersion, adding a low content of ethylene-propylene copolymer-based PP-g-MA compatibilizer having a high MA-grafting level, and a polar organoclay (Cloisite®30B is the most desirable formulation to optimize clay intercalation and exfoliation in PP-g-starch. Nevertheless, regarding the reinforcement effect, whatever the PP-g-MA compatibilizer, the addition of non polar organoclay (Cloisite®20A is preferably recommended to reach higher tensile properties (modulus, yield stress, strength without significant loss of ductility.

  17. Increased oral bioavailability of paclitaxel by its encapsulation through complex formation with cyclodextrins in poly(anhydride) nanoparticles.

    Science.gov (United States)

    Agüeros, M; Zabaleta, V; Espuelas, S; Campanero, M A; Irache, J M

    2010-07-01

    The aim of this work was to study the oral bioavailability in rats of paclitaxel (PTX) when encapsulated as a complex with cyclodextrins in poly(anhydride) nanoparticles (NP). For this purpose three different cyclodextrins were selected: beta-cyclodextrin (CD), 2-hydroxypropyl-beta-cyclodextrin (HPCD) and 6-monodeoxy-6-monoamino-beta-cyclodextrin (NHCD). A single dose of 10mg paclitaxel per kg body weight as PTX-cyclodextrin nanoparticles was used. Plasma curves were characterised by a plateau of paclitaxel concentration close to the C(max) from T(max) till 24h post-administration. For PTX-CD NP and PTX-HPCD NP, these sustained levels of the anticancer drug were found to be between 27 and 33-fold higher than the reported value of drug activity whereas the relative oral bioavailability of paclitaxel was calculated to be higher than 80%. These facts would be directly related with a synergistic effect obtained by the combination of the bioadhesive properties of poly(anhydride) nanoparticles and the inhibitory effect of cyclodextrins on the activity of P-glycoprotein and cythocrome P450.

  18. Using maleic anhydride functionalized graphene oxide for improving the interfacial properties of carbon fiber/BMI composites

    Directory of Open Access Journals (Sweden)

    W. Li

    2016-11-01

    Full Text Available Maleic anhydride functionalized graphene oxide (MAH-GO was synthesized and then introduced into carbon fiber (CF reinforced bismaleimide (BMI composites, with the aim of improving the interfacial adhesion strength between CF and BMI resin. Various characterization techniques including Fourier transform infrared spectroscopy (FT-IR, X-ray photoelectron spectra (XPS and thermogravimetric analysis (TGA demonstrated that the maleic anhydride has been successfully grafted onto the GO surfaces. The study showed that the interlaminar shear strength (ILSS and flexural properties of CF/BMI composites were all improved by the incorporation of GO and MAH-GO, and the MAH-GO showed the substantially improved effect due to the strong interaction between the MAH-GO and the resin matrix. The maximum increment of the ILSS, flexural strength and flexural modulus of composites were 24.4, 28.7 and 49.7%, respectively. Scanning electron microscope (SEM photographs of the fracture surfaces revealed that the interfacial bonding between CF and resin matrix was significantly strengthened by the addition of MAH-GO. The results suggest that this feasible method may be an ideal substitute for the traditional method in the interfacial modification of composites.

  19. Anhydride functionalised calcium ferrite nanoparticles: a new selective magnetic material for enrichment of lead ions from water and food samples.

    Science.gov (United States)

    Pirouz, Mojgan Jafari; Beyki, Mostafa Hossein; Shemirani, Farzaneh

    2015-03-01

    In this research a sonochemistry route for manufacture of uniform nanocrystalline CaFe2O4 and its anhydride functionalisation were reported. The potential of raw and modified material as a magnetically separable sorbent in selective enrichment of lead ions from water and food samples is outlined. This material was characterised using FT-IR, XRD, SEM and VSM techniques. The SEM and VSM results indicated that the calcium ferrite nanoparticles are sphere-like particles possessing superparamagnetic properties with an average diameter of 40 nm. Various analytical parameters, including pH, contact time, type and concentration of eluent, adsorption capacity, sample volume and interference of ions, were optimised. Following a modification by anhydride, calcium ferrite selectivity toward lead ions was raised more than twofold compared to the unmodified nanoparticles. Finally a pre-concentration procedure was applied for determination of trace Pb(II) in canned tuna fish, canned tomato paste, parsley, milk and well-water samples with satisfactory results.

  20. Process Formulations And Curing Conditions That Affect Saltstone Properties

    Energy Technology Data Exchange (ETDEWEB)

    Reigel, M. M.; Pickenheim, B. R.; Daniel, W. E.

    2012-09-28

    The first objective of this study was to analyze saltstone fresh properties to determine the feasibility of reducing the formulation water to premix (w/p) ratio while varying the amount of extra water and admixtures used during processing at the Saltstone Production Facility (SPF). The second part of this study was to provide information for understanding the impact of curing conditions (cure temperature, relative humidity (RH)) and processing formulation on the performance properties of cured saltstone.

  1. The curing process of layered silicate/epoxy nanocomposites

    OpenAIRE

    Nieminen, Ilkka

    2009-01-01

    The industrial methods of processing polymeric thermoset matrix nanocomposites require a good knowledge of the matrix curing process. The dispersion of nanoparticles in the matrix effects the curing process due to the interaction between nanoparticles and the matrix at the atomic level, especially when the nanoparticles have been treated with a surfactant agent ( alquilammonium) that is in competition with the reactive groups of the hardener. This thesis investigates the curing process o...

  2. Optical fibre grating refractometers for resin cure monitoring

    Science.gov (United States)

    Buggy, S. J.; Chehura, E.; James, S. W.; Tatam, R. P.

    2007-06-01

    The use of fibre grating refractometers as a means of monitoring the cure of a UV-cured epoxy resin is presented. The wavelength shift of the attenuation bands of a long period grating and the spectral response of a tilted fibre Bragg grating sensor were measured simultaneously during the cure of the resin and compared with measurements made using a fibre optic Fresnel-based refractometer. The results showed a good correlation (6 × 10-3 rius) and illustrate the potential of the techniques for non-invasive composite material cure monitoring.

  3. Curing Methods and Their Effects on The Strength of Concrete

    OpenAIRE

    Nuruddeen Usman; Muhammad Nura Isa

    2015-01-01

    There are a lot of arguments on which method of curing concrete gives good strength. These different opinions results into this study, which aim at investigating the effects of different curing methods on the strength of concrete. Laboratory test was employed for this study. Normal concretes were prepared using specified mix ratio of 1:2:4 and 1:3:6. The cubes tested for compressive strength at 3, 7, 21, and 28 days of curing respectively using four curing methods namely immersion...

  4. Ambient Cured Alkali Activated Flyash Masonry Units

    Science.gov (United States)

    Venugopal, K.; Radhakrishna; Sasalatti, Vinod M.

    2016-09-01

    Geopolymers belong to a category of non-conventional and non-Portland cement based cementitious binders which are produced using industrial by products like fly ash and ground granulated blast furnace slag (GGBFS). This paper reports on the development of geopolymer mortars for production of masonry units. The geopolymer mortars were prepared by mixing various by products with manufactured sand and a liquid mixture of sodium silicate and sodium hydroxide solutions. After curing at ambient conditions, the masonry units were tested for strength properties such as water absorption, initial rate of absorption, compression, shear- bond, and stress-strain behaviour etc. It was observed that the flexural strength of the blocks is more than 2 MPa and shear bond strength is more than 0.4MPa. It was found that the properties of geopolymer blocks were superior to the traditional masonry units. Hence they can be recommended for structural masonry.

  5. Helicobacter pylori: Basic Mechanisms to Clinical Cure

    Directory of Open Access Journals (Sweden)

    ABR Thomson

    1995-01-01

    Full Text Available Since its rediscovery 10 years ago, Helicobacter pylori has reshaped our thinking about the course of peptic ulcer disease. Our approach to the patient with a duodenal ulcer has become one of attempting eradication therapy at the time of first diagnosis, in the hope of curing the ulcer disease. Gastric and duodenal ulceration are only two of the manifestations of this chronic antral infection; other complications of H pylori include gastritis, gastric cancer and possible maltomas. Therapy of H pylori infection is complicated and involves dual therapy with an antibiotic plus a protein pump inhibitor, such as omeprazole 20 mg bid plus amoxicillin 1 g bid for two weeks, triple or quadruple therapy with bismuth, two antibiotics and an H2-receptor antagonist. Vaccination against H pylori is on the far horizon.

  6. Brane polarization is no cure for tachyons

    CERN Document Server

    Bena, Iosif

    2015-01-01

    Anti-M2 and anti-D3 branes placed in regions with charges dissolved in fluxes have a tachyon in their near-horizon region, which causes these branes to repel each other. If the branes are on the Coulomb branch this tachyon gives rise to a runaway behavior, but when the branes are polarized into five-branes this tachyon only appears to lower the energy of the polarized branes, without affecting its stability. We analyze brane polarization in the presence of a brane-brane-repelling tachyon and show that when the branes are polarized along the direction of the tachyon the polarized shell is unstable. This implies that tachyons cannot be cured by brane polarization and indicates that, at least in a certain regime of parameters, anti-D3 branes polarized into NS5 branes at the bottom of the Klebanov-Strassler solution have an instability.

  7. Stratospheric experiments on curing of composite materials

    Science.gov (United States)

    Chudinov, Viacheslav; Kondyurin, Alexey; Svistkov, Alexander L.; Efremov, Denis; Demin, Anton; Terpugov, Viktor; Rusakov, Sergey

    2016-07-01

    Future space exploration requires a large light-weight structure for habitats, greenhouses, space bases, space factories and other constructions. A new approach enabling large-size constructions in space relies on the use of the technology of polymerization of fiber-filled composites with a curable polymer matrix applied in the free space environment on Erath orbit. In orbit, the material is exposed to high vacuum, dramatic temperature changes, plasma of free space due to cosmic rays, sun irradiation and atomic oxygen (in low Earth orbit), micrometeorite fluence, electric charging and microgravitation. The development of appropriate polymer matrix composites requires an understanding of the chemical processes of polymer matrix curing under the specific free space conditions to be encountered. The goal of the stratospheric flight experiment is an investigation of the effect of the stratospheric conditions on the uncured polymer matrix of the composite material. The unique combination of low residual pressure, high intensity UV radiation including short-wave UV component, cosmic rays and other aspects associated with solar irradiation strongly influences the chemical processes in polymeric materials. We have done the stratospheric flight experiments with uncured composites (prepreg). A balloon with payload equipped with heater, temperature/pressure/irradiation sensors, microprocessor, carrying the samples of uncured prepreg has been launched to stratosphere of 25-30 km altitude. After the flight, the samples have been tested with FTIR, gel-fraction, tensile test and DMA. The effect of cosmic radiation has been observed. The composite was successfully cured during the stratospheric flight. The study was supported by RFBR grants 12-08-00970 and 14-08-96011.

  8. Curing of epoxy matrix composite in stratosphere

    Science.gov (United States)

    Kondyurin, Alexey; Kondyurina, Irina; Bilek, Marcela

    Large structures for habitats, greenhouses, space bases, space factories are needed for next stage of space exploitation. A new approach enabling large-size constructions in space relies on the use of the polymerization technology of fiber-filled composites with a curable polymer matrix applied in the free space environment. The polymerisation process is proposed for the material exposed to high vacuum, dramatic temperature changes, space plasma, sun irradiation and atomic oxygen (in low Earth orbit), micrometeorite fluence, electric charging and microgravitation. The stratospheric flight experiments are directed to an investigation of the curing polymer matrix under the stratospheric conditions on. The unique combination of low atmospheric pressure, high intensity UV radiation including short wavelength UV and diurnal temperature variations associated with solar irradiation strongly influences the chemical processes in polymeric materials. The first flight experiment with uncured composites was a part of the NASA scientific balloon flight program realised at the NASA stratospheric balloon station in Alice Springs, Australia. A flight cassette installed on payload was lifted with a “zero-pressure” stratospheric balloon filled with Helium. Columbia Scientific Balloon Facility (CSBF) provided the launch, flight telemetry and landing of the balloon and payload. A cassette of uncured composite materials with an epoxy resin matrix was exposed 3 days in the stratosphere (40 km altitude). The second flight experiment was realised in South Australia in 2012, when the cassette was exposed in 27 km altitude. An analysis of the chemical structure of the composites showed, that the space irradiations are responsible for crosslinking of the uncured polymers exposed in the stratosphere. The first prepreg in the world was cured successfully in stratosphere. The investigations were supported by Alexander von Humboldt Foundation, NASA and RFBR (12-08-00970) grants.

  9. Influence of curing tip distance on resin composite Knoop hardness number, using three different light curing units.

    Science.gov (United States)

    Caldas, Danilo Biazzetto de Menezes; de Almeida, Janaina Bertoncelo; Correr-Sobrinho, Lourenço; Sinhoreti, Mário Alexandre Coelho; Consani, Simonides

    2003-01-01

    This in vitro study evaluated the influence of curing tip distance on the Knoop Hardness Number (KHN) of a resin composite when using three different light curing units: (1) a halogen light (XL 1500 curing unit-3M), (2) a "softstart-polymerization" (Elipar Trilight curing in an exponential mode-ESPE) and (3) a PAC (Apolo 95E curing unit-DMD). The resin composite, Filtek Z250 (3M), was cured by these curing units at three light-tip distances from the resin composite: 0 mm, 6 mm and 12 mm. The resin composite specimens were flattened to their middle portion and submitted to 18 KHN measurements perspecimen. The results showed that for the Elipar Trilight unit, the hardness of the resin composite decreased as the light tip distance increased. The XL 1500 unit presented a significant decrease in hardness as the depth of cure of the resin composite increased. Apolo 95E caused a decrease in the resin composite hardness values when the depth of cure and light tip distance increased.

  10. The effect of curing time and curing method on microleakge of conservative adhesive resin restorations: an in vitro study

    Directory of Open Access Journals (Sweden)

    Alireza Heidari

    2012-01-01

    Full Text Available Background and Aims: Using the conservative adhesive resin restoration (CAR in uncooperative children lead to numerous problems because of being time consuming. The purpose of this study was to compare the microleakage of conservative adhesive resin restoration under separate curing and co-curing.Materials and Methods: In this experimental study, 120 intact premolar teeth were collected and 120 vertical grooves were prepared on them. Then the teeth were divided into four groups: group 1, separated curing of bonding agent, flowable composite and sealant; group 2, co-curing of all materials for 60 seconds; group 3,co-curing of all materials for 40 seconds and group 4, co-curing of all materials for 20 seconds. Then the specimens were thermocycled and immersed in basic fuchsin solution. The teeth were sectioned horizontally and dye penetration was evaluated with stereomicroscope. Date were analyzed using one-way ANOVA and Scheffe test.Results: Mean value of dye penetration in groups 1, 2, 3, and 4 was 1.53±0.6, 2.06±0.6, 2.5±0.7 and 3.53±0.6, respectively. There was a statistically significant difference between group 1 and the other groups (P=0.0001.Conclusion: Considering the problems caused by microleakage in conservative resin adhesive restorations, co-curing method should not be used. In the case of using co-curing method, 60 second curing time is suggested for sufficient polymerization.

  11. Micromechanical properties of veneer luting resins after curing through ceramics.

    Science.gov (United States)

    Oztürk, Elif; Hickel, Reinhard; Bolay, Sükran; Ilie, Nicoleta

    2012-02-01

    The aim of this study was to assess the performance of light-cured luting resin after curing under the ceramic restoration in comparison to dual-cured luting resin, by evaluating the micromechanical properties. Two hundred seventy thin luting composite films of ca. 170 μm in thickness were prepared by using two light-cured luting resins (Variolink Veneer, Ivoclar Vivadent; RelyX Veneer, 3M ESPE) and a dual-cured luting resin (Variolink II, Ivoclar Vivadent). The composites were cured by using a LED-unit (Bluephase®, Ivoclar Vivadent) with three different curing times (10, 20, and 30 s) under two ceramics (IPS e.max Press, Ivoclar Vivadent; IPS Empress® CAD, Ivoclar Vivadent) of different thicknesses (0, 0.75, and 2 mm). Forty-five groups were included, each containing six thin films. The samples were stored after curing for 24 h at 37°C by maintaining moisture conditions with distilled water. Micromechanical properties of the composites were measured with an automatic microhardness indenter (Fisherscope H100C, Germany). For each sample, ten indentations were made, thus totalizing 60 measurements per group. Micromechanical properties of the luting resins were statistically analyzed (SPSS 17.0). Significant differences were observed between the micromechanical properties of the luting resins (p mechanical properties compared to the light-cured luting resins. The effect of luting resin type on the micromechanical properties of the luting resins was higher than the effect of curing time, ceramic type and ceramic thickness respectively (*The values of reference without ceramics for 30 s curing time).

  12. Estudio cinético del efecto de polifenilsulfona sobre el curado de una resina epoxi/amina mediante calorimetría diferencial de barrido convencional y modulada con temperatura: parte II Kinetic study on the effect of curing polyphenylsulfone epoxy resin/amina by differential calorimetry scanning conventional and modulated temperature: part II

    Directory of Open Access Journals (Sweden)

    Asdrúbal J. Cedeño

    2010-01-01

    Full Text Available En este trabajo se estudió el efecto de la adición del termoplástico lineal polifenilsulfona (PPSU, sobre la cinética de reacción y las propiedades térmicas de una resina epoxídica basada en diglicidil éter de bisfenol - A (DGEBA, curada con diaminodifenilsulfona (DDS. El estudio cinético y la caracterización se realizaron mediante calorimetría diferencial de barrido, DSC estándar y modulado, bajo condiciones isotérmicas y dinámicas. La cinética del curado se discutió en el marco de tres modelos cinéticos: Kissinger, Flynn-Wall-Ozawa y el modelo cinético de orden n. Para describir la reacción de curado en su última etapa, se usó la relación semiempírica propuesta por Chern y Poehlein para considerar la influencia de la difusión sobre la rapidez de reacción. El mecanismo de curado, para todos los sistemas, se ajustó a una cinética de orden n, a pesar del contenido de PPSU, y se observó que éste se hace muy controlado por la difusión conforme aumenta el contenido de PPSU y conforme la temperatura de curado disminuye. El tiempo de vitrificación de los sistemas exhibió una fuerte dependencia con el contenido de PPSU.In this work we studied the effect of the addition of the linear thermoplastic polyphenyl sulfone (PPSU on the cure kinetics and the thermal properties of a resin based on diglycidyl ether of bisphenol-A (DGEBA, cured with 4,4´-diaminodiphenyl sulfone (DDS. The kinetic study and the characterization process have been carried out by using differential scanning calorimetry, DSC, and temperature modulated DSC (TMDSC, under isothermal and dynamic conditions. The curing kinetics was discussed in the framework of three kinetic models: Kissinger, Flynn-Wall-Ozawa, and the model of reaction of order n. To describe the cured reaction in its last stage, we have used the semiempirical relationship proposed by Chern and Poehlein to take into account the influence of diffusion on the reaction rate. The cure mechanism

  13. Hardening of a dual-cure resin cement using QTH and LED curing units

    OpenAIRE

    Santos,Maria Jacinta Moraes Coelho; Passos, Sheila Pestana; Encarnação, Monalisa Olga Lessa da; Santos Junior,Gildo Coelho; Bottino, Marco Antonio [UNESP

    2010-01-01

    p. 110-115 OBJECTIVE: This study evaluated the surface hardness of a resin cement (RelyX ARC) photoactivated through indirect composite resin (Cristobal) disks of different thicknesses using either a light-emitting diode (LED) or quartz tungsten halogen (QTH) light source. MATERIAL AND METHODS: Eighteen resin cement specimens were prepared and divided into 6 groups according to the type of curing unit and the thickness of resin disks interposed between the cement surface and light sourc...

  14. ACID RESISTANCE OF FLYASH BASED GEOPOLYMER MORTAR UNDER AMBIENT CURING AND HEAT CURING

    Directory of Open Access Journals (Sweden)

    V.Sreevidya

    2012-02-01

    Full Text Available An Experimental study was conducted to assess the Acid resistance of flyash based geopolymer mortar specimens of size 50x50x50mm with a ratio of flyash to sand as 1:3.The ratio between solution(Sodiumhydroxide and Sodium silicate solution to flyash were 0.376,0.386,0.396 and 0.416. After casting the specimens were subjected to both ambient curing and heat curing. In heat curing the specimens were kept continuously at 60oC for 24 hrs. Durability of specimens was assessed by immersing them in 5% of sulfuric acid and 5%hydrochloric acid for a period of 14 weeks. Evaluation of its resistance in terms of change in weight, compressive strength and visual appearance at regular intervals was carried out. After exposure in the acid solutions for 14 weeks, the samples showed very low weight loss. Results obtained from the present study indicate that Geopolymers are highly resistance to sulfuric acid and hydrochloric acid.

  15. Improved method facilitates debulking and curing of phenolic impregnated asbestos

    Science.gov (United States)

    Gaines, P.

    1966-01-01

    Workpieces covered with phenolic impregnated asbestos tape and then wrapped with a specified thickness of nylon yarn under pressure, are debulked and cured in a standard oven. This method of debulking and curing is used in the fabrication of ablative chambers for the Gemini and Apollo attitude control engines.

  16. Isothermal epoxy-cure monitoring using nonlinear ultrasonics

    NARCIS (Netherlands)

    Koissin, V.; Demcenko, A.; Korneev, V.A.

    2014-01-01

    Isothermal curing of LY 1564SP resin in an aluminium-adhesive-aluminium laminate is investigated, using a nonlinear ultrasonic immersion technique, to prove its applicability for this type of dynamic material transformation. For verification and comparison, epoxy-cure kinetics and rheological behavi

  17. Shortest exposure time possible with LED curing lights

    NARCIS (Netherlands)

    Busemann, I.; Lipke, C.; Schattenberg, A.V.M.B.; Willershausen, B.; Ernst, C.P.

    2011-01-01

    PURPOSE: To investigate the shortest exposure time of different light emitting diode (LED)-curing devices for different resin composites in a clinically relevant laboratory model. METHODS: Nine LED curing devices (Bluephase, Bluephase 16i, Bluephase G2, Bluephase 20i/Ivoclar Vivadent, DEMI/sds Kerr,

  18. Curing mechanism of alkaline phenolic resin with organic ester

    Institute of Scientific and Technical Information of China (English)

    Huang Renhe; Wang Yanmin; Zhang Baoping

    2014-01-01

    To study the curing mechanism of alkaline phenolic resin with organic ester, three esters were chosen to react with three systems - alkaline phenolic resin, potassium hydroxide aqueous solution containing phenol, and potassium hydroxide aqueous solution. The variations of pH, heat release and gel pH during the reactions were monitored and measured. Infrared spectroscopy (IR) and thermal gravity analysis (TG) techniques were used to characterize the curing reaction. It was found that organic ester is only partial y hydrolyzed and resin can be cured through organic ester hydrolysis process as wel as the reaction with redundant organic ester. The sequential curing mechanism of alkaline phenolic resin cured by organic ester was identified as fol ows: a portion of organic ester is firstly hydrolyzed owing to the effect of the strong alkaline; the gel is then formed after the pH decreases to about 10.8-10.88, meanwhile, the redundant organic ester (i.e. non-hydrolysis ester) starts the curing reaction with the resin. It has also been found that the curing rate depends on the hydrolysis velocity of organic ester. The faster the hydrolysis speed of the ester, the faster the curing rate of the resin.

  19. ORGANIC/INORGANIC HYBRID EPOXY NANOCOMPOSITES BASED ON OCTA(AMINOPHENYL)SILSESQUIOXANE

    Institute of Scientific and Technical Information of China (English)

    Hai-bo Fan; Rong-jie Yang; Xiang-mei Li

    2013-01-01

    Octa(aminophenyl)silsesquioxane (OAPS) was used as the curing agent of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin.A study on comparison of DGEBA/OAPS with DGEBA/4,4'-diaminodiphenyl sulfone (DDS) epoxy resins was achieved.Differential scanning calorimetry was used to investigate the curing reaction and its kinetics,and the glass transition of DGEBA/OAPS.Thermogravimetric analysis was used to investigate thermal decomposition of the two kinds of epoxy resins.The reactions between amino groups and epoxy groups were investigated using Fourier transform infrared spectroscopy.Scanning electron microscopy was used to observe morphology of the two epoxy resins.The results indicated that OAPS had very good compatibility with DGEBA in molecular level,and could form a transparent DGEBA/OAPS resin.The curing reaction of the DGEBA/OAPS prepolymer could occur under low temperatures compared with DGEBA/DDS.The DGEBA/OAPS resin didn't exhibit glass transition,but the DGEBA/DDS did,which meant that the large cage structure of OAPS limited the motion of chains between the cross-linking points.Measurements of the contact angle indicated that the DGEBA/OAPS showed larger angles with water than the DGEBA/DDS resin.Thermogravimetric analysis indicated that the incorporation of OAPS into epoxy system resulted in low mass loss rate and high char yield,but its initial decomposition temperature seemed to be lowered.

  20. Greener Friedel-Crafts Acylation using Microwave-enhanced reactivity of Bismuth Triflate in the Friedel-Crafts Benzoylation of Aromatic Compounds with Benzoic Anhydride

    DEFF Research Database (Denmark)

    Tran, Phuong Hoang; Nguyen, hai Truong; Hansen, Poul Erik

    2017-01-01

    An efficient and facile bismuth trifluoromethanesulfonate-catalyzed benzoylation of aromatic compounds using benzoic anhydride under solvent-free microwave irradiation has been developed. The microwave-assisted Friedel-Crafts benzoylation results in good yields within short reaction times. Bismut...

  1. Characterization of differently sized granule fractions of yellow pea, cowpea and chickpea starches after modification with acetic anhydride and vinyl acetate

    NARCIS (Netherlands)

    Huang, J.; Schols, H.A.; Jin, Z.; Sulmann, E.; Voragen, A.G.J.

    2007-01-01

    The effect of reagent type on the properties of acetylated starches was studied for yellow pea, cowpea and chickpea starches after modification with acetic anhydride and vinyl acetate. Samples modified with vinyl acetate showed higher swelling volume and peak viscosity than those acetylated with ace

  2. An atom-economic approach to carboxylic acids via Pd-catalyzed direct addition of formic acid to olefins with acetic anhydride as a co-catalyst.

    Science.gov (United States)

    Wang, Yang; Ren, Wenlong; Shi, Yian

    2015-08-21

    An effective Pd-catalyzed hydrocarboxylation of olefins using formic acid with acetic anhydride as a co-catalyst is described. A variety of carboxylic acids are obtained in good yields with high regioselectivities under mild reaction conditions without the use of toxic CO gas.

  3. Characterization of maleic acid/anhydride copolymer films by low-rate dynamic liquid-fluid contact angle measurements using axisymmetric drop shape analysis.

    Science.gov (United States)

    Uhlmann, Petra; Skorupa, Sebastian; Werner, Carsten; Grundke, Karina

    2005-07-05

    Thin films of alternating maleic acid/anhydride copolymers (poly(octadecene-alt-maleic acid/anhydride), POMA; poly(propene-alt-maleic acid/anhydride), PPMA; poly(styrene-alt-maleic acid/anhydride), PSMA) were studied to unravel the influence of the comonomer characteristics in the backbone on the surface-energetic properties of the copolymer films in the dry state and in contact with aqueous solutions. Water contact angle measurements revealed a graduation of the wettability of the dry hydrolyzed and annealed copolymer films that was dependent on the comonomer unit. It ranged from moderately hydrophilic (PPMA, annealed gamma(sv) = 39.9 mJ/m2) to very hydrophobic (POMA, annealed, gamma(sv) = 18.4 mJ/m2) surfaces. Liquid-fluid contact angle measurements using captive air bubbles were performed in different aqueous media (pure water, phosphate-buffered saline, and 10(-)(3) M KCl of two different pH values (pH = 3 and pH = 10) to study the copolymer films in their hydrated states relevant for biointerfacial phenomena. It was found that the graduation of the wettability of the copolymer films in the dry state is overall maintained upon immersion in aqueous solutions. The dependence of the wettability on the pH value of the aqueous medium could be related to the (de)protonation of the carboxylic groups.

  4. 40 CFR 721.3635 - Octadecanoic acid, ester with 1,2-propanediol, phosphate, anhydride with silicic acid (H4SiO4).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Octadecanoic acid, ester with 1,2..., ester with 1,2-propanediol, phosphate, anhydride with silicic acid (H4SiO4). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as octadecanoic acid,...

  5. Development of various curing effect of nominal strength Geopolymer concrete

    Directory of Open Access Journals (Sweden)

    S. Kumaravel

    2014-04-01

    Full Text Available Geopolymer concrete is an innovative method and is produced by complete elimination of ordinary Portland cement byproduced in fly ash. This study on different condition of curing in geopolymer concrete suitable for curing at ambient and heat-cured condition of temperature will widen its application to concrete structures. Low lime fly ash is used as the base material, which is reacted by alkaline solution and additional use of ground granulated blast furnace slag. Workability of fresh concrete and compressive strength of geopolymer concrete was investigated. The curing effect of geopolymer concrete is steam, hot air and ambient cubes specimens are tested in different days. Results are compared for various curing and strength of concrete.

  6. STUDY ON THE POST-CURE KINETICS OF EPOXY RESIN IRRADIATED BY AN ELECTRON BEAM

    Institute of Scientific and Technical Information of China (English)

    Jian-wen Bao; Ye Li; Xiang-yu Zhong; Xiang-bao Chen; Feng-mei Li

    2004-01-01

    The post-cure kinetics of electron beam (EB) curing of epoxy resin initiated by diaryiodinium was investigated.The post-cure reaction fits first order reaction kinetics. The reaction rate constant increases with increasing treatment temperature of post-cure. The reaction rate of post-cure is much lower than the rate of its reaction on electron beam treatment.

  7. High-Strain Rate Mechanical Response of Cured Epoxy Networks

    Science.gov (United States)

    Sirk, Timothy; Khare, Ketan; Karim, Mir; Lenhart, Joseph; Khare, Rajesh; Andzelm, Jan

    2013-03-01

    Chemically cross-linked polymer networks are increasingly common in high performance composites, adhesives and other applications involving high-impact loading conditions or ballistic collisions. The mechanical behavior of epoxy and other polymer networks exhibit a strong dependence on strain rate near the glass transition temperature (Tg); however, the elastic modulus at strain rates greater than 105 1/s is difficult to capture with experimental techniques. We present computational results of Di-Glycidyl Ether of Bisphenol A (DGEBA) and Jeffamine diamines (D230) from molecular dynamics simulation, which is intrinsically well-suited to model material deformation at high strain rates. Our results show that the experimental Tg can be reproduced from molecular dynamics, and the Williams-Landel-Ferry equation is useful in rationalizing the shift of Tg due to fast annealing and high strain rates. Temperature sweeps of elastic modulus show the glass-rubber transition to occur over a significantly wider temperature range compared with experimental measurements at low strain rates.

  8. Chitosan: poly(N-vinylpyrrolidone-alt-itaconic anhydride) nanocapsules—a promising alternative for the lung cancer treatment

    Energy Technology Data Exchange (ETDEWEB)

    Raţă, Delia Mihaela, E-mail: iureadeliamihaela@yahoo.com [„Apollonia” University of Iasi, Faculty of Medical Dentistry, „Academician Ioan Haulică” Research Institute (Romania); Chailan, Jean-François, E-mail: chailan@univ-tln.fr [University of Sud Toulon-Var, « Matériaux-Polymères-Interfaces-Environnement Marin (MAPIEM) Laboratory (France); Peptu, Cătălina Anişoara, E-mail: catipeptu@yahoo.co.uk [“Gheorghe Asachi” Technical University of Iasi, Department of Natural and Synthetic Polymers, Faculty of Chemical Engineering and Environmental Protection (Romania); Costuleanu, Marcel, E-mail: mcostuleanu@yahoo.com [University of Medicine and Pharmacy “Grigore T. Popa”- Iaşi, Department of General Pathology, Faculty of Dental Medicine (Romania); Popa, Marcel, E-mail: marpopa2001@yahoo.fr [“Gheorghe Asachi” Technical University of Iasi, Department of Natural and Synthetic Polymers, Faculty of Chemical Engineering and Environmental Protection (Romania)

    2015-07-15

    This study reports the preparation of novel polymeric nanocapsules based on a natural polymer, chitosan and a synthetic one, poly(N-vinylpyrrolidone-alt-itaconic anhydride) [(poly(NVPAI)] using an interfacial condensation technique. The infrared spectroscopy studies confirmed the crosslinking through the presence of amide bonds, formed between the two polymers chains. The diameter of nanocapsules was found in the range of 126–214 nm and it was determined by dynamic light scattering method. Morphological characterization demonstrated their nano size, the spherical shape of the nanocapsules and the formation of hollow particles. The nanocapsules presented good swelling capacity in aqueous solutions. 5-Fluorouracil (5-FU) loading and release capacity was studied, the processes being controlled by the drug diffusion through the polymeric membrane. The obtained results were encouraging, showing that 5-FU-loaded nanocapsules had 70 % higher apoptotic effect on A549 tumour cells than the drug in free state or mixed with the nanocapsules.

  9. Plasma Polymerized Thin Films of Maleic Anhydride and 1,2-methylenedioxybenzene for Improving Adhesion to Carbon Surfaces

    DEFF Research Database (Denmark)

    Drews, Joanna Maria; Goutianos, Stergios; Kingshott, Peter

    2007-01-01

    Low power 2-phase AC plasma polymerization has been used to surface modify glassy carbon substrates that are used as an experimental model for carbon fibers in reinforced composites. In order to probe the role of carboxylic acid density on the interfacial adhesion strength a combination...... of different plasma powers and monomer compositions was used. Maleic anhydride (MAR) and 1,2-methylenedioxybenzene (MDOB) were plasma deposited separately and as mixtures to create layers with different surface compositions. In all cases the MAR was hydrolyzed to form carboxylic acid groups. Some carboxylic...... total veflectanc~ Fourier transform infrared spectroscopy. Atomic force microscopy was used to measure the thickness of the plasma films and to monitor the surface roughness for the different polymerization conditions. Finally, preliminary results of fracture energy measurements of the plasma modified...

  10. LITHIUM ION CONDUCTING POLYMER ELECTROLYTES BASED ON ALTERNATING MALEIC ANHYDRIDE COPOLYMER WITH OLIGO-OXYETHYLENE SIDE CHAINS

    Institute of Scientific and Technical Information of China (English)

    DING Liming

    1996-01-01

    A comb polymer with oligo-oxyethylene side chains of the type -(CH2CH2O)12CH3 was prepared from methyl vinyl ether/maleic anhydride copolymer and poly (ethylene glycol) methyl ether. The polymer can dissolve LiClO4 salt to form homogeneous amorphous polymer electrolyte. The ac ion conduction was measured using the complex impedance method, and conductivities were investigated as functions of temperatures and salt concentration. The complexes were first found to have two classes of glass transition which increase with increasing salt content. The optimum conductivity attained at 25℃ is in the order of 5.50 × 10-6Scm-1. IR spectroscopy was used to study the cation-polymer interaction.

  11. Chitosan: poly( N-vinylpyrrolidone- alt-itaconic anhydride) nanocapsules—a promising alternative for the lung cancer treatment

    Science.gov (United States)

    Raţă, Delia Mihaela; Chailan, Jean-François; Peptu, Cătălina Anişoara; Costuleanu, Marcel; Popa, Marcel

    2015-07-01

    This study reports the preparation of novel polymeric nanocapsules based on a natural polymer, chitosan and a synthetic one, poly( N-vinylpyrrolidone- alt-itaconic anhydride) [(poly(NVPAI)] using an interfacial condensation technique. The infrared spectroscopy studies confirmed the crosslinking through the presence of amide bonds, formed between the two polymers chains. The diameter of nanocapsules was found in the range of 126-214 nm and it was determined by dynamic light scattering method. Morphological characterization demonstrated their nano size, the spherical shape of the nanocapsules and the formation of hollow particles. The nanocapsules presented good swelling capacity in aqueous solutions. 5-Fluorouracil (5-FU) loading and release capacity was studied, the processes being controlled by the drug diffusion through the polymeric membrane. The obtained results were encouraging, showing that 5-FU-loaded nanocapsules had 70 % higher apoptotic effect on A549 tumour cells than the drug in free state or mixed with the nanocapsules.

  12. Deactivation properties of a high-productive vanadia-titania catalyst for oxidation of o-xylene to phthalic anhydride

    Directory of Open Access Journals (Sweden)

    A. T. Georgieva

    2008-06-01

    Full Text Available The behavior of a high-productive V2O5-TiO2 (anatase supported O 4-28 catalyst for oxidation of o-xylene to phthalic anhydride was investigated in the first three years of its exploitation in industry. By using a suitable mathematical model, an identification problem was solved and activation profiles of the catalyst along a fixed bed located in the tubes of an industrial reactor were determined. Experimental temperature regimes and yields of the main and side products for different periods of the catalyst life were used. The proper technological regimes providing for a maximum yield according to the requirements of the catalyst producer company were defined.

  13. Synthesis of 1H-benzoxazine-2,4-diones from heterocyclic anhydrides: evaluation of antioxidant and antimicrobial activities

    Directory of Open Access Journals (Sweden)

    Juan I. Sarmiento-Sánchez

    2014-01-01

    Full Text Available A facile one-step synthesis of 1H-benzoxazine-2,4-diones from heterocyclic anhydrides and TMSA was described. This paper determines their antimicrobial activity against nine human bacterial pathogens by the broth microdilution method; antioxidant activity by DPPH• inactivation and a ferric-reducing power assay; and toxicity by a brine shrimp, Artemia salina, assay. The 1H-benzoxazine-2,4-dione yields were in the range of 57 to 98%. The novel compound 1H-pyrazino[2,3-][1,3]oxazine-2,4-dione 4c showed the highest antioxidant capacity (DPPH 35.4% and FRAP 0.063 µmol TEs/µmol.

  14. Grafting of copolymer styrene maleic anhydride on poly(ethylene terephthalate) film by chemical reaction and by plasma method

    Energy Technology Data Exchange (ETDEWEB)

    Bigan, Muriel; Bigot, Julien [Laboratoire de Chimie Organique et Macromoleculaire (UMR 8009), Universite des Sciences et Technologies de Lille, 59655 Villeneuve d' Ascq Cedex (France); Mutel, Brigitte [Laboratoire de Genie des Procedes d' Interactions Fluides reactifs-Materiaux (UPRES-EA 3751), Batiment C5, Universite des Sciences et Technologies de Lille, 59655 Villeneuve d' Ascq Cedex (France)], E-mail: Brigitte.mutel@univ-lille1.fr; Coqueret, Xavier [Laboratoire Reactions Selectives et Applications (UMR-CNRS 6519) Universite de Reims Champagne-Ardennes, B.P. 1039, 51687 Reims Cedex 2 (France)

    2008-02-15

    This work deals with the chemical grafting of a styrene maleic anhydride copolymer on the surface of a previously hydrolyzed polyethylene terephthalate (PET) film 12 {mu}m thick via covalent bond. Two different ways are studied. The first one involves an activation of the hydrolyzed PET by the triethylamine before the grafting step. In the second one, the copolymer reacts with the 4-dimethylaminopyridine in order to form maleinyl pyridinium salt which reacts with alcohol function of the hydrolyzed PET. Characterization and quantification of the grafting are performed by Fourier transform infrared spectroscopy. Factorial experiment designs are used to optimize the process and to estimate experimental parameters effects. The opportunity to associate the chemical process to a cold remote nitrogen plasma one is also examined.

  15. Effect of wood acetylation with vinyl acetate and acetic anhydride on the properties of wood-plastic composites

    Directory of Open Access Journals (Sweden)

    Nilgül Özmen

    2013-02-01

    Full Text Available Chemical modifications of Scots pine (Pinus slyvestris wood flour were performed with vinyl acetate (VA and acetic anhydride (AA in the presence of potassium carbonate as a catalyst. Scots pine wood flour samples were successfully acetylated with VA (19 wt% gain and AA (24 wt% gain. The effect of chemical modification of the Scots pine wood flour with AA and VA on the mechanical properties of wood high-density polyethylene composites (WPC were determined. It was observed that acetylation of wood flour allowed a significant increase in both the mechanical properties and the thermal stability of the WPCs. It was concluded that acetylation of lignocellulosic fibers improves thermal stability, dispersion in the polymer matrix, and compatibility with the polymer matrix.

  16. Acylation Modification of Antheraea pernyi Silk Fibroin Using Succinic Anhydride and Its Effects on Enzymatic Degradation Behavior

    Directory of Open Access Journals (Sweden)

    Xiufang Li

    2013-01-01

    Full Text Available The degradation rate of tissue engineering scaffolds should match the regeneration rate of new tissues. Controlling the degradation behavior of silk fibroin is an important subject for silk-based tissue engineering scaffolds. In this study, Antheraea pernyi silk fibroin was successfully modified with succinic anhydride and then characterized by zeta potential, ninhydrin method, and FTIR. In vitro, three-dimensional scaffolds prepared with modified silk fibroin were incubated in collagenase IA solution for 18 days to evaluate the impact of acylation on the degradation behavior. The results demonstrated that the degradation rate of modified silk fibroin scaffolds was more rapid than unmodified ones. The content of the β-sheet structure in silk fibroin obviously decreased after acylation, resulting in a high degradation rate. Above all, the degradation behavior of silk fibroin scaffolds could be regulated by acylation to match the requirements of various tissues regeneration.

  17. Polycarbonate/Polypropylene-Graft-Maleic Anhydride and Nano-Zeolite-Based Nanocomposite Membrane: Mechanical and Gas Separation Performance

    Directory of Open Access Journals (Sweden)

    Kausar A.

    2016-12-01

    Full Text Available In this effort, blend membrane of polycarbonate (PC and polypropylene-graft-maleic anhydride (PPMA was fabricated via phase inversion technique. The nano-zeolite (NZ was employed as nanofiller. Morphology of PC/PPMA/NZ membrane revealed unique inter-connected branched microstructure. Tensile strength and Young’s Modulus of PC/PPMA/NZ 0.1-5 were in the range of 59.9-74.5 MPa and 111.4-155.2 MPa respectively. The nano-zeolite filler was also effective in enhancing the permselectivity αCO2/N2 (23.5 to 38.5 relative to blend membrane (20.3. The permeability PCO2 of PC/PPMA/NZ 5 membrane was found as 106.2 Barrer. Filler loading enhanced gas diffusivity, however filler content did not significantly influence CO2 and N2 solubility.

  18. Preparation and Characterization of Extruded Composites Based on Polypropylene and Chitosan Compatibilized with Polypropylene-Graft-Maleic Anhydride

    Directory of Open Access Journals (Sweden)

    Fernando Javier Carrasco-Guigón

    2017-01-01

    Full Text Available The preparation of composites of synthetic and natural polymers represent an interesting option to combine properties; in this manner, polypropylene and chitosan extruded films using a different proportion of components and polypropylene-graft-maleic anhydride (PPgMA as compatibilizer were prepared. The effect of the content of the biopolymer in the polypropylene (PP matrix, the addition of compatibilizer, and the particle size on the properties of the composites was analyzed using characterization by fourier transform-infrared spectroscopy (FT-IR, scanning electron microscopy (SEM, differential scanning calorimetry (DSC, tensile strength, and contact angle, finding that in general, the addition of the compatibilizer and reducing the particle size of the chitosan, favored the physicochemical and morphological properties of the films.

  19. Novel high glass temperature sugar-based epoxy resins: Characterization and comparison to mineral oil-based aliphatic and aromatic resins

    Directory of Open Access Journals (Sweden)

    P. Niedermann

    2015-02-01

    Full Text Available Curing and rheological behaviour, glass transition temperature, mechanical and thermal properties of two newly synthesized glucopyranoside- (GPTE and glucofuranoside- (GFTE based renewable epoxy resin (EP components were investigated and compared to aromatic and aliphatic EPs. The glucose-based EPs can be successfully cured with amine and anhydride type curing agents, their gel times are suitable for processing and can be well-adopted to the needs of the common composite preparation methods. GPTE showed the highest glass transition temperature (Tg among all investigated resins, followed by GFTE and DGEBA. Below the Tg there was no significant difference between the storage modulus values of the EP systems. The glucose-based EPs had lower tensile and bending strength, but their tensile modulus values are not significantly different from the mineral oil based EPs. The thermal stability of the synthesized GPTE and GFTE is between DGEBA and the aliphatic resins. In applications where bending stresses are dominant over the tensile ones, and outstanding Tg is required, these glucose-based resins offer a feasible renewable option.

  20. Variation of Resin Properties Through the Thickness of Cured Samples

    Science.gov (United States)

    1984-01-01

    It is the purpose of this work to gain knowledge of the glassy materials used as matrices in composites and to study the homogeneity resulting from the curing process. An attempt is made to link the glass transition quantitatively with the presence of a given material. Expoxy resins containing various amounts of hardener (TGDDM/DDS system) were cured in a muffle furnace at 473 K for seven hours. The glass transition temperature, T sub g versus weight minus percent of hardener in the epoxy resin were measured. A limit was rapidly reached in T sub g at only two percent hardener. Thus, the glass transition of the fully cured epoxy-amine matrix seems not much different from the epoxide-epoxide cure. The T sub g versus cure-time for the epoxide-epoxide reaction was also studied. My 720 was cured by itself in an oil bath at 473 K for different lengths of time. The T sub g was found to increase exponentially with the cure time, and a maximum T sub g of about 450 K was reached after eleven hours. The reaction was found to be inhibited by running the sample under argon.

  1. Development of Geopolymer Concrete with Different Curing Conditions

    Directory of Open Access Journals (Sweden)

    M.F. Nuruddin Nuruddin

    2011-02-01

    Full Text Available Environmental issues resulted from cement production have become a major concern today. To develop a sustainable future it is encouraged to limit the use of this construction material that can affect the environment. Cement replacement material was proposed to partially replace cement portion in concrete. Geopolymer is a part of inorganic polymer material that has similar bonding function like cement in concrete. It consists of alkaline solutions and geological source material. Alkaline liquids used in this research are 8 M sodium hydroxide (NaOH solution and sodium silicate (Na2SiO3 solutions, while source materials are fly ash and microwave incinerated rice husk ash (MIRHA. Three different curing regimes, namely hot gunny curing, ambient curing, and external exposure curing, were applied to obtain suitable method that was suitable with cast in situ application. Geopolymer concrete samples were tested on their compressive strength and microstructure properties. It was found that external exposure curing had the highest compressive strength compared to other two curing methods. Scanning electron microscopy analysis also showed better improvement in interfacial transition zone for concrete sample with external exposure curing.

  2. Electron Beam Cured Epoxy Resin Composites for High Temperature Applications

    Science.gov (United States)

    Janke, Christopher J.; Dorsey, George F.; Havens, Stephen J.; Lopata, Vincent J.; Meador, Michael A.

    1997-01-01

    Electron beam curing of Polymer Matrix Composites (PMC's) is a nonthermal, nonautoclave curing process that has been demonstrated to be a cost effective and advantageous alternative to conventional thermal curing. Advantages of electron beam curing include: reduced manufacturing costs; significantly reduced curing times; improvements in part quality and performance; reduced environmental and health concerns; and improvement in material handling. In 1994 a Cooperative Research and Development Agreement (CRADA), sponsored by the Department of Energy Defense Programs and 10 industrial partners, was established to advance the electron beam curing of PMC technology. Over the last several years a significant amount of effort within the CRADA has been devoted to the development and optimization of resin systems and PMCs that match the performance of thermal cured composites. This highly successful materials development effort has resulted in a board family of high performance, electron beam curable cationic epoxy resin systems possessing a wide range of excellent processing and property profiles. Hundreds of resin systems, both toughened and untoughened, offering unlimited formulation and processing flexibility have been developed and evaluated in the CRADA program.

  3. A 'cure' for Down syndrome: what do parents want?

    Science.gov (United States)

    Inglis, A; Lohn, Z; Austin, J C; Hippman, C

    2014-10-01

    Recent advancements in molecular genetics raise the possibility that therapeutics or a 'cure' for Down syndrome (DS) may become available. However, there are no data regarding how parents of children with DS perceive the possibility of mitigating specific manifestations such as the intellectual disability (ID) associated with DS, or curing the condition entirely. To explore these issues, we distributed a questionnaire to members of the Lower Mainland Down Syndrome Society in British Columbia, Canada. Questionnaires were completed by 101 parents (response rate=41%). A majority (61%) viewed the possibility of reversing ID in DS positively, but only 41% said that they would 'cure' their child of DS if it were possible. Twenty-seven percent of respondents said they would not 'cure' their child, and 32% were unsure if they would 'cure' their child. The most commonly cited motivation for opting for a 'cure' was to increase their child's independence. However, parental attitudes' towards a 'cure' for DS were complex, affected by ethical issues, perceived societal values, and pragmatic factors such as the age of the individual and long-term care-giving burden. These findings could be used by healthcare professionals supporting families who include a member with DS and to direct future research.

  4. Composite depth of cure using four polymerization techniques

    Directory of Open Access Journals (Sweden)

    Ericson Janolio de Camargo

    2009-10-01

    Full Text Available The light-curing technique is relevant to reduce the degree of polymerization shrinkage, improving clinical and esthetic success of composite resin restorations. OBJECTIVE: To evaluate in vitro the effect of four light-curing techniques on depth of cure of a composite resin. MATERIAL AND METHODS: Ten specimens of a composite resin were made in cylindrical cavities prepared in PVC plates (3.0 X 7.0 mm for each light-curing technique. Four photoactivation methods were investigated: stepped, ramped, pulse-delay and traditional. Specimens were longitudinally sectioned and polished for microhardness measurements (kg/mm², which were made at 0.1, 1.0, 2.0 and 4.0 mm from the irradiated surface. Data were subjected to ANOVA and Tukey's test. RESULTS: The effect of factors studied (curing method and distance from the surface and the interaction of these factors was statistically significant (p<0.05. The traditional method of cure provided higher microhardness values (69.6 ± 2.5 than the stepped (63.5 ± 3.1 and pulsed (63.9 ± 3.2 methods at all depths evaluated, but it did not differ from the ramped method (66.7± 4.4 at 0.1 and 1.0 mm of depth. CONCLUSION: All techniques employed provided satisfactory cure of the composite resin up to the depth of 2.0 mm from the irradiated surface.

  5. Development of a resin curing model for UV nanoimprint.

    Science.gov (United States)

    Lee, Jin Woo; Cho, Dong-Woo

    2005-10-01

    UV nanoimprint lithography uses UV light as an energy source. It is performed at room temperature and low pressure, and has its own merits as compared to thermal nanoimprint. In this paper, a measurement system was developed to measure the degree of resin curing in UV nanoimprint to improve our understanding of the resin solidification phenomenon. A curing model was then established based on the measurement results. The measurement system measured the degree of cure in real time and was composed of a Fourier transform infrared spectroscopy system, a UV light source, and an optical guide. Also, new UV-curable resins that had low viscosity values were developed for the UV nanoimprint process, and imprint tests using these resins were performed successfully. The curing model considered the UV irradiation time, power, and curing temperature, which are important parameters in the UV nanoimprint process. The degree of cure had an exponential relation to UV irradiation time, power, and temperature; thus, the curing model was expressed as an exponential function of the UV irradiation time, power, and temperature. The developed model was verified for various UV-curable resins.

  6. Changes on degree of conversion of dual-cure luting light-cured with blue LED

    Science.gov (United States)

    Bandéca, M. C.; El-Mowafy, O.; Saade, E. G.; Rastelli, A. N. S.; Bagnato, V. S.; Porto-Neto, S. T.

    2009-05-01

    The indirect adhesive procedures constitute recently a substantial portion of contemporary esthetic restorative treatments. The resin cements have been used to bond tooth substrate and restorative materials. Due to recently introduction of the self-bonding resin luting cement based on a new monomer, filler and initiation technology has become important to study the degree of conversion of these new materials. In the present work the polymerization reaction and the filler content of dual-cured dental resin cements were studied by means of infra-red spectroscopy (FT-IR) and thermogravimetry (TG). Twenty specimens were made in a metallic mold (8 mm diameter × 1 mm thick) from each of 2 cements, Panavia® F2.0 (Kuraray) and RelyX™ Unicem Applicap (3M/ESPE). Each specimen was cured with blue LED with power density of 500 mW/cm2 for 30 s. Immediately after curing, 24 and 48 h, and 7 days DC was determined. For each time interval 5 specimens were pulverized, pressed with KBr and analyzed with FT-IR. The TG measurements were performed in Netzsch TG 209 under oxygen atmosphere and heating rate of 10°C/min from 25 to 700°C. A two-way ANOVA showed DC (%) mean values statistically significance differences between two cements ( p 0.05). The Relx-Y™ Unicem mean values were significantly higher than Panavia® F 2.0. The degree of conversion means values increasing with the storage time and the filler content showed similar for both resin cements.

  7. Experimental observation of internal water curing of concrete

    DEFF Research Database (Denmark)

    Lura, Pietro; Jensen, Ole Mejlhede

    2007-01-01

    Internal water curing has a significant effect on concrete. In addition to affecting hydration and moisture distribution, it influences most concrete properties, such as strength, shrinkage, cracking, and durability. The following paper is an overview of experimental methods to study internal water...... curing of concrete and its consequences. The special techniques needed to study internal water curing are dealt with along with the consequences of this process. Examples of applications are given and new measuring techniques that may potentially be applied to this field are addressed....

  8. Micro-leakage of a Fissure Sealant Cured Using Quartz-tungsten-halogen and Plasma Arc Light Curing Units.

    Science.gov (United States)

    Bahrololoomi, Zahra; Soleimani, Ali Asghar; Jafari, Najmeh; Varkesh, Bentolhoda

    2014-01-01

    Background and aims. Newer curing units such as plasma arc can polymerize the sealants in much shorter curing times. The aim of this study was to compare the effect of two different curing units on the micro-leakage of a fissure sealant material. Materials and methods. Sixty two extracted premolars without caries were randomly divided into two groups of 31 samples. Occlusal surfaces of all teeth were cleansed. Then, teeth surfaces were etched by 37% phosphoric acid. After rinsing and drying, occlusal surfaces of teeth were sealed by a fissure sealant. The sealant was then cured using either a halogen light curing unit or a plasma arc curing light. After sealing, the teeth were thermocycled for 500 cycles. The teeth were then sectioned and examined for micro-leakage. Statistical analyses were performed with Mann-Whitney test. Results. There was no significant difference between two groups regarding micro-leakage (P = 0.42). Conclusion. Results showed that there was no significant difference between two different curing units. Therefore, plasma arc unit might be a useful alternative for sealant polymerization.

  9. Measuring Vapors To Monitor the State of Cure of a Resin

    Science.gov (United States)

    Cramer, Elliott; Perey, Daniel F.; Yost, William T.

    2006-01-01

    A proposed noninvasive method of monitoring the cure path and the state of cure of an epoxy or other resin involves measurement of the concentration( s) of one or more compound(s) in the vaporous effluent emitted during the curing process. The method is based on the following general ideas: (1) The concentrations of the effluent compounds in the vicinity of the curing resin are approximately proportional to the instantaneous rate of curing. (2) As curing proceeds at a given temperature, subsequent decreases in the concentrations are indicative of approaching completion of cure; that is, the lower are the concentrations, the more nearly complete is the cure.

  10. The effect of curing light and chemical catalyst on the degree of conversion of two dual cured resin luting cements.

    Science.gov (United States)

    Souza-Junior, Eduardo José; Prieto, Lúcia Trazzi; Soares, Giulliana Panfiglio; Dias, Carlos Tadeu dos Santos; Aguiar, Flávio Henrique Baggio; Paulillo, Luís Alexandre Maffei Sartini

    2012-01-01

    The aim of this study was to evaluate the influence of different curing lights and chemical catalysts on the degree of conversion of resin luting cements. A total of 60 disk-shaped specimens of RelyX ARC or Panavia F of diameter 5 mm and thickness 0.5 mm were prepared and the respective chemical catalyst (Scotchbond Multi-Purpose Plus or ED Primer) was added. The specimens were light-cured using different curing units (an argon ion laser, an LED or a quartz-tungsten-halogen light) through shade A2 composite disks of diameter 10 mm and thickness 2 mm. After 24 h of dry storage at 37°C, the degree of conversion of the resin luting cements was measured by Fourier-transformed infrared spectroscopy. For statistical analysis, ANOVA and the Tukey test were used, with p ≤ 0.05. Panavia F when used without catalyst and cured using the LED or the argon ion laser showed degree of conversion values significantly lower than RelyX ARC, with and without catalyst, and cured with any of the light sources. Therefore, the degree of conversion of Panavia F with ED Primer cured with the quartz-tungsten-halogen light was significantly different from that of RelyX ARC regardless of the use of the chemical catalyst and light curing source. In conclusion, RelyX ARC can be cured satisfactorily with the argon ion laser, LED or quartz-tungsten-halogen light with or without a chemical catalyst. To obtain a satisfactory degree of conversion, Panavia F luting cement should be used with ED Primer and cured with halogen light.

  11. Comparative Study of Alkali-Activated Fly Ash Manufactured Under Pulsed Microwave Curing and Thermal Oven Curing

    OpenAIRE

    Shi, Shi; Bai, Yun; Li, H.; Xu, D. L.; Basheer, P. A. Muhammed

    2014-01-01

    This paper compares the alkali-activated fly ash (AAFA) manufactured with thermal oven curing and pulsed microwave curing methods. Fly ash activated by 8M NaOH solution at a liquid to solid ratio of 0.3 was cured by thermal oven at 85°C and domestic microwave oven, respectively. Apart from compressive strength test, the temperature profiles of AAFA samples were captured by thermal camera. Reaction products of AAFA were characterised with XRD, FTIR and TG/DTG, while the microstructure of AAFA ...

  12. A micro-Raman study of Cu-particulate-filled epoxy matrix composites

    Directory of Open Access Journals (Sweden)

    S. Tognana

    2014-05-01

    Full Text Available A micro-Raman study is carried out to investigate the influence of the filler on the curing process of bisphenol A diglycidyl ether (DGEBA-based epoxy matrix composites. The composites are cured (14 h at 393 K with an anhydride (methyl tetrahydro phthalic anhydride, MTHPA, 100:90 pbw, catalyzed with a tertiary amine (0.7 pbw and filled with a 30% volume of Cu particles of approximately 75 µm in diameter. The experimental results are compared with those obtained for the same epoxy resin unfilled and for the same composite with Cu filler but not catalyzed. The micro-Raman experimental technique is used to search for information on the curing process in different regions of the matrix, near to and far from the copper filler, taking into account the results of differential-scanning-calorimetry measurements performed on the same composites. The results provide information on the influence of the copper filler on the curing process of the epoxy matrix. Differences were observed in the peaks associated with the epoxy ring and the ester group as a function of the distance to the nearest copper particle, but no differences were observed between the different composites.

  13. Chemistry and technology of Cured and Smoked Meat Products

    Directory of Open Access Journals (Sweden)

    V. K. Mathur

    1967-05-01

    Full Text Available Recent developments in the chemistry and technology of cured and smoked meat products are reviewed. Various factors physical, chemical and microbiological affecting water holding capacity of cured meats and cured colour formation and its stability during storage are discussed. Methods of preparation of various types of cured and smoked meat products have been briefly described. Developments in the use of synthetic casings and skinless sausages have been mentioned. Smoke constituents, their role and physico-chemical aspects of mechanism and functions of smoking are discussed. Advancements in the methods of smoke generation, conventional smoking and some kilns, electrostatic smoking and smoking by use of liquid smokes have been described. Some of the methods of preparation of liquid smokes are also given.

  14. Cure monitoring using ultrasonic guided waves in wires

    Science.gov (United States)

    Vogt, T.; Lowe, M.; Cawley, P.

    2003-09-01

    The possibility of using ultrasonic guided waves for monitoring the cure process of epoxy resins is investigated. The two techniques presented use a wire waveguide which is partly embedded in the resin. The first technique is based on the measurement of attenuation due to leakage of bulk waves into the resin surrounding the waveguide. The second technique measures the reflection of the guided wave that occurs at the point where the waveguide enters the resin. Both the attenuation and the reflection coefficient change significantly during cure, and the numerical methods to relate these to the material properties of the curing resin are presented in this paper. The results from the modeling are experimentally verified and show good agreement. The applicability of each testing method is discussed, and typical cure-monitoring curves are presented.

  15. Curing of Epoxy Resin Induced by Femtosecond Laser Pulse

    Institute of Scientific and Technical Information of China (English)

    LI Yubin; ZHANG Zuoguang

    2005-01-01

    The possibility of curing of epoxy resin induced by femtosecond laser beam was explored through choosing different initiators . Absorption spectroscopy, infrared spectroscopy (IR), stereomicroscopy and scanning electron microscopy (SEM) were applied to analyze the structure of epoxy resin systems after irradiation with a femtosecond laser beam. The experimental results show that the epoxy resin systems containing diaryliodonium salts can be cured by irradiation of Jemtosecond laser pulse, while the systems containing benzoin can not be cured. It is found that diaryliodonium salts decompose under the irradiation of femtosecond laser pulse through multi ( two ) -photon absorption, initiating the ring-opening polymerization of epoxy resin. And the appearance of cured area has a sheet structure consisting of many tiny lamellar structures.

  16. GENERAL ENVIRONMENTAL CORPORATION; CURE ELECTROCOAGULATION TECHNOLOGY: INNOVATIVE TECHNOLOGY EVALUATION REPORT

    Science.gov (United States)

    The CURE electrocoagulation technology was demonstrated under the Superfund Innovative Technology Evaluation (SITE) program at the U.S. Department of Energy (DOE) Rocky Flats Environmental Technology Site (RFETS), where water from the solar evaporation ponds (SEPs) was contaminat...

  17. Cure monitoring using ultrasonic guided waves in wires.

    Science.gov (United States)

    Vogt, T; Lowe, M; Cawley, P

    2003-09-01

    The possibility of using ultrasonic guided waves for monitoring the cure process of epoxy resins is investigated. The two techniques presented use a wire waveguide which is partly embedded in the resin. The first technique is based on the measurement of attenuation due to leakage of bulk waves into the resin surrounding the waveguide. The second technique measures the reflection of the guided wave that occurs at the point where the waveguide enters the resin. Both the attenuation and the reflection coefficient change significantly during cure, and the numerical methods to relate these to the material properties of the curing resin are presented in this paper. The results from the modeling are experimentally verified and show good agreement. The applicability of each testing method is discussed, and typical cure-monitoring curves are presented.

  18. Factors affecting dry-cured ham consumer acceptability.

    Science.gov (United States)

    Morales, R; Guerrero, L; Aguiar, A P S; Guàrdia, M D; Gou, P

    2013-11-01

    The objectives of the present study were (1) to compare the relative importance of price, processing time, texture and intramuscular fat in purchase intention of dry-cured ham through conjoint analysis, (2) to evaluate the effect of dry-cured ham appearance on consumer expectations, and (3) to describe the consumer sensory preferences of dry-cured ham using external preference mapping. Texture and processing time influenced the consumer preferences in conjoint analysis. Red colour intensity, colour uniformity, external fat and white film presence/absence influenced consumer expectations. The consumer disliked hams with bitter and metallic flavour and with excessive saltiness and piquantness. Differences between expected and experienced acceptability were found, which indicates that the visual preference of consumers does not allow them to select a dry-cured ham that satisfies their sensory preferences of flavour and texture.

  19. The Prevention and Cure of Cervical Vertebra Disease

    Institute of Scientific and Technical Information of China (English)

    1994-01-01

    CERVICAL vertebra problems are common and usually occur in middleaged and elderly people, especially those who often bend over. The symptoms patients might encounter are dizziness, headache, neck and shoulder pain and numbness, and even viscera trouble. The following exercises are a simple and convenient way to prevent and cure cervical vertebra problems. If you continue doing the exercises, you can prevent and cure them. Here are the exercises step by step:

  20. Cure Characteristics of Tricyanate Ester High Temperature Composite Resins (PREPRINT)

    Science.gov (United States)

    2011-02-09

    isothermal DSC data were analyzed via the Kissinger [17], Ozawa [18], and Friedman [19] methods, as described in the recent analysis of dicyanate ester...7 present the graphical analysis that underlies the Kissinger [17], Ozawa [18], and Friedman [19] methods, respectively, of non-isothermal DSC cure...where β is the heating rate and Tp the absolute temperature at the peak cure rate, is proportional to the activation energy. For the Ozawa method

  1. In-situ cure monitoring of epoxy resin systems

    OpenAIRE

    Powell, Graham

    1998-01-01

    This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University. This thesis describes the work carried out at Brunel University to develop novel optical fibre sensors capable of monitoring the cure state of an epoxy/amine resin system. The sensors were of simple construction, consisting of an optical fibre from which the silicone cladding layer had been removed over a short length. This stripped length was embedded into the curing resin system. The sensor...

  2. Manufacturing of vegetable oils-based epoxy and composites for structural applications

    Science.gov (United States)

    Wang, Rongpeng

    Epoxidized vegetable oil (EVO) is one of the largest industrial applications of vegetable oils (VOs) and is widely used as a plasticizer and as a synthetic intermediate for polyol or unsaturated polyester. However, the utility of EVO as monomer for high performance epoxy thermoset polymer is limited by its reactivity and by the resulting physical properties. Herein, VO-based epoxy monomers, i.e., glycidyl esters of epoxidized fatty acids derived from soybean oil (EGS) or linseed oil (EGL), have been synthesized and were benchmarked against commercial available diglycidyl ether of bisphenol A (DGEBA) and also epoxidized soybean oil (ESO) controls. EGS and EGL possessed higher oxirane content, more reactivity and lower viscosity than ESO or epoxidized linseed oil (ELO), provided better compatibility with DGEBA as a reactive diluent, and yielded thermally and mechanically stronger polymers than polymers obtained using ESO. Glass transition temperatures (T g) of the VO-based epoxy thermoset polymers were mostly a function of monomer oxirane content with some added structural influences of epoxy reactivity, and presence of a pendant chain. Organo-modified montmorillonite clay (OMMT) and long glass fiber reinforced composites (FRC) were efficiently manufactured using anhydride cured EGS as matrices. The OMMT nanocomposites showed higher mechanical and thermal strength than the neat polymers but were also dependent on the dispersion techniques and the clay concentration. Surprisingly, the neat EGS-anhydride matrix FRC showed comparable properties, such as flexural and impact strengths and slightly lower Tg, versus DGEBA based counterparts. These high performance monomers, polymers, and composites have potential to replace petroleum-based epoxy as value-added products from VOs compared to EVOs.

  3. CURING PROCESS OF PHOTOPOLYMER RESIN BOND DIAMOND TOOLS

    Institute of Scientific and Technical Information of China (English)

    GAO Tao; PENG Wei; YAO Chunyan

    2007-01-01

    Analytical simulation and corresponding proof-test are adopted to study the principle of the curing process of photopolymer resin diamond tools. The influence of the diamond as abrasives in photopolymer resin owing to the absorptivity of the diamond for the UV light on the photopolymer resin curing process is discussed. Based on the above, a kind of diamond tool-dicing blade is selected to analyze the curing process of photopolymer bond diamond tools. An analytical model of curing process is developed and a correlation curve between the depth of polymerization of the photopolymer resin diamond tools and the exposure time to represent the curing process of photopolymer bond dicing blade. A test is done to proof-test the validity of the analytical model and the correlation curve. The simulated data fit the experimental results, which demonstrates the analytical models and numerical algorithm are of high reliability. The analytical simulation method could possibly be used to optimize the curing cycle and improve the quality of the photopolymers resin bond diamond tools.

  4. Monitoring the Cure State of Thermosetting Resins by Ultrasound

    Directory of Open Access Journals (Sweden)

    Alfonso Maffezzoli

    2013-09-01

    Full Text Available The propagation of low intensity ultrasound in a curing resin, acting as a high frequency oscillatory excitation, has been recently proposed as an ultrasonic dynamic mechanical analysis (UDMA for cure monitoring. The technique measures sound velocity and attenuation, which are very sensitive to changes in the viscoelastic characteristics of the curing resin, since the velocity is related to the resin storage modulus and density, while the attenuation is related to the energy dissipation and scattering in the curing resin. The paper reviews the results obtained by the authors’ research group in the last decade by means of in-house made ultrasonic set-ups for both contact and air-coupled ultrasonic experiments. The basics of the ultrasonic wave propagation in polymers and examples of measurements of the time-evolution of ultrasonic longitudinal modulus and chemical conversion of different thermosetting resins are presented. The effect of temperature on the cure kinetics, the comparison with rheological, low frequency dynamic mechanical and calorimetric results, and the correlation between ultrasonic modulus and crosslinking density will be also discussed. The paper highlights the reliability of ultrasonic wave propagation for monitoring the physical changes taking place during curing and the potential for online monitoring during polymer and polymer matrix composite processing.

  5. Depth of cure of bulk-fill flowable composite resins.

    Science.gov (United States)

    Pedalino, Inaam; Hartup, Grant R; Vandewalle, Kraig S

    2015-01-01

    In recent years, manufacturers have introduced flowable composite resins that reportedly can be placed in increments of 4 mm or greater. The purpose of this study was to evaluate the depth of cure of bulk-fill flowable composite resins (SureFil SDR Flow, Grandio Flow, and Venus Bulk Fill) and a conventional flowable composite resin (Revolution Formula 2). Depth of cure was measured in terms of bottom-maximum Knoop hardness number (KHN) ratios and the International Organization for Standardization (ISO) 4049 scrape technique. Shades A2 and A3 of SureFil SDR Flow, Grandio Flow, and Revolution Formula 2 were tested. Venus Bulk Fill was tested in its only available shade (universal). Specimens in thicknesses of 2, 3, 4, 5, and 6 mm were polymerized for 20 or 40 seconds, and a hardness tester was used to determine the hardness ratios for each shade at each thickness. For the scraping technique, after specimens were exposed to the curing light, unpolymerized composite resin was removed with a plastic instrument, the polymerized composite was measured, and the length was divided by 2 per ISO guidelines. According to the KHN ratios and the scrape test, Venus Bulk Fill predictably exceeded the manufacturer's claim of a 4-mm depth of cure at both 20 and 40 seconds of curing time. The overall results for depth of cure showed that Venus Bulk Fill ≥ SureFil SDR Flow ≥ Grandio Flow ≥ Revolution Formula 2.

  6. 海因环氧树脂/HHPA体系的制备与性能%Synthesize Hydantoin Epoxy and Preparation Cured Hydantoin Epoxy/HHPA

    Institute of Scientific and Technical Information of China (English)

    李玲; 田晋丽; 陈剑楠

    2012-01-01

    Hydantoin epoxy resin was synthesized and hydantoin epoxy in presence of hexahydroph-thalic anhydride (HHPA) as the curing agent was preparation. Hydantoin epoxy resin was substantiated by FTIR and 1 H-NMR spectrum. Non-isothermal differential scanning calorimetry (DSC) was examined to follow the curing reaction of hydantoin epoxy/HHPA system. Epoxy equivalent of hydantoin epoxy resin is 164g equiv : and viscosity is 6. 9Pa · S at 25°C which the closed to diglycidyl ether of bisphenol FCCYDF-180). The DSC analyses showed that there are an exothermic reaction peak from 90℃ to 210°C for the hydantoin epoxy/HHPA system and top of the peak is 152. 5℃ at 10℃/min,which determined main reaction of hydantoin epoxy/HHPA system. The curing process temperatures such as gel temperature (Tge1) =93. 7℃ , curing temperature (Tp) = 136. 9℃ and post-curing temperature (Ttreat) =181. 2℃ were acquired by extrapolation, which confirmed a lowering of the cure temperature of the hydantoin epoxy/HHPA system to avoid defect formation. Curing characterization of hydantoin epoxy resin is the similar with diglycidyl ether of bisphenol A. The hydantoin epoxy/HHPA cured resin was made and its properties were studied. Investigations show that the flex-ural strength is 122MPa, flexural modul is 2. 8GPa, impact strength is 14. 9kJ/m2,and limit oxygen index is 23 which indicates mechanical properties of hydantoin epoxy resin exceeds diglycidyl ether of bisphenol A. Therefore hydantoin epoxy resin can a candidate matrix for performance composite material manufacture and adhesive application in automobile industries, shipbuilding, aerospace, laminates and insulation material.%合成了海因环氧树脂,采用红外光谱和核磁共振进行了表征,以六氢苯酐(HHPA)为固化剂,制备了海因环氧树脂/HHPA体系,研究了海因环氧树脂/HHPA体系的固化反应性及其固化物的性能.结果表明:树脂体系在升温速率为10℃/min的条件下,在90~210℃有

  7. SYNTHESIS OF MESOPOROUS POLY(STYRENE-co-MALEIC ANHYDRIDE)/SILICA HYBRID MATERIALS VIA A NONSURFACTANT-TEMPLATED SOL-GEL PROCESS

    Institute of Scientific and Technical Information of China (English)

    Jie-bin Pang; Kun-yuan Qiu; Yen Wei

    2000-01-01

    Mesoporous poly(styrene-co-maleic anhydride)/silica hybrid materials have been prepared. The synthesis was achieved by the HCl-catalyzed sol-gel reactions of tetraethyl orthosilicate (TEOS) and styrene-maleic anhydride copolymer in the presence of 3-aminopropyl triethoxysilane (APTES) as a coupling agent and citric acid as a nonsurfactant template or pore-forming agent, followed by ethanol extraction. Characterization results from nitrogen sorption isotherms and powder Xray diffraction indicate that polymer-modified mesoporous materials with large specific surface areas (e.g. 900 m2/g) and pore volumes (e.g. 0.6 cm3/g) could be prepared. As the citric acid concentration is increased, the specific surface areas, pore volumes and pore diameters of the hybrid materials increase.

  8. Mixed anhydrides (phosphoric-carboxyl) are also formed in the esterification of 5'-amp with n-acetylaminoacyl imidazolides - Implications regarding the origin of protein synthesis

    Science.gov (United States)

    Wickramasinghe, Nalinie S. M. D.; Lacey, James C., Jr.

    1992-01-01

    Procedure for the formation of aminoacyl esters of monoribonucleotides with aminoacyl imidazolides were first reported by Gottikh et al. (1970) and summarized in 1970. This reaction has been widely used by us and numbers of other workers as a convenient means of preparing aminoacyl esters of nucleotides. We have previously reported that, under conditions of excess imidazolide, large amounts of bis 2', 3' esters are formed in addition to the monoesters. However, to our knowledge, no one has reported that in addition to the esters, relatively large amounts of the mixed anhydride, with the amino acid carboxyl attached to the phosphate, are also formed at short reaction times. We report here on the relative amounts of anhydride and esters formed in this reaction of racemic mixtures of eleven N-acetyl amino acid imidazolides with 5'-AMP and discuss the relevance of the findings to the origin of protein synthesis.

  9. Efficient synthesis of zinc-containing mesoporous silicas by microwave irradiation method and their high activities in acetylation of 1,2-dimethoxybenzene with acetic anhydride

    Directory of Open Access Journals (Sweden)

    K. Bachari

    2016-09-01

    Full Text Available A series of acid zinc-containing mesoporous materials have been synthesized by microwave irradiation method with different Si/Zn ratios (Si/Zn = 100, 65, 15 and characterized by several spectroscopic techniques such as: N2 physical adsorption, ICP, XRD, TEM, FT-IR and a temperature-programmed-desorption (TPD of pyridine. The liquid phase of acetylation of 1,2-dimethoxybenzene with acetic anhydride has been investigated over this series of catalysts. In fact, the catalyst Zn-JLU-15 (15 showed bigger performance in the acid-catalyzed acetylation of 1,2-dimethoxybenzene employing acetic anhydride as an acylating agent. Furthermore, the kinetics of the acetylation of 1,2-dimethoxybenzene over these catalysts have also been investigated.

  10. Electronic Effects of Aluminum Complexes in the Copolymerization of Propylene Oxide with Tricyclic Anhydrides: Access to Well-Defined, Functionalizable Aliphatic Polyesters.

    Science.gov (United States)

    Van Zee, Nathan J; Sanford, Maria J; Coates, Geoffrey W

    2016-03-02

    The synthesis of well-defined and functionalizable aliphatic polyesters remains a key challenge in the advancement of emerging drug delivery and self-assembly technologies. Herein, we investigate the factors that influence the rates of undesirable transesterification and epimerization side reactions at high conversion in the copolymerization of tricyclic anhydrides with excess propylene oxide using aluminum salen catalysts. The structure of the tricyclic anhydride, the molar ratio of the aluminum catalyst to the nucleophilic cocatalyst, and the Lewis acidity of the aluminum catalyst all influence the rates of these side reactions. Optimal catalytic activity and selectivity against these side reactions requires a careful balance of all these factors. Effective suppression of undesirable transesterification and epimerization was achieved even with sterically unhindered monomers using a fluorinated aluminum salph complex with a substoichiometric amount of a nucleophilic cocatalyst. This process can be used to synthesize well-defined block copolymers via a sequential addition strategy.

  11. Rubber-Modified Epoxies. II. Morphology, Transitions, and Mechanical Properties.

    Science.gov (United States)

    1984-11-01

    tetrafunctional aromatic diamine-cured diglycidyl ether of bisphenol A ( DGEBA )-type epoxy resin was selected as the neat system because of its high ETgm (1670C...was a DGEBA -type epoxy resin (DER 331, Dow Chemical Co.) cured with tri- methylene glycol di-p-aminobenzoate (ITMABO, i.e. Polacure 740M, Polaroid...Chemical "o.) with excess of DGEBA resin. The second system, denoted DTAxl6, was iodified with a commercial amino-terminated butadiene-acrylonitrile

  12. The Effect of Mould Size on the Exothermic Reaction and Compressive Strength of Epoxy Resin Chocks.

    Science.gov (United States)

    1984-12-01

    referred to as exotherm, may reach 260 0 C for DGEBA systems cured at room temperature. [Ref. 8] D. PREVIOUS WORK Research has been conducted by...epichlorohydrin and bisphenol A, the reac- tion giving diglycidyl ether of bisphenol A ( DGEBA ). [Ref. 6] Although the specific manufacturing process of...CHOCKFAST ORANGE was not provided, the major constituent is DGEBA . 13 The compound cures and solidiries in 12 to 48 hours, dependent on ambient

  13. Degree of cure-dependent modelling for polymer curing processes at small-strain. Part I: consistent reformulation

    Science.gov (United States)

    Hossain, M.; Steinmann, P.

    2014-04-01

    A physically-based small strain curing model has been developed and discussed in our previous contribution (Hossain et al. in Comput Mech 43:769-779, 2009a) which was extended later for finite strain elasticity and viscoelasticity including shrinkage in Hossain et al. (Comput Mech 44(5):621-630, 2009b) and in Hossain et al. (Comput Mech 46(3):363-375, 2010), respectively. The previously proposed constitutive models for curing processes are based on the temporal evolution of the material parameters, namely the shear modulus and the relaxation time (in the case of viscoelasticity). In the current paper, a thermodynamically consistent small strain constitutive model is formulated that is directly based on the degree of cure, a key parameter in the curing (reaction) kinetics. The new formulation is also in line with the earlier proposed hypoelastic approach. The curing process of polymers is a complex phenomenon involving a series of chemical reactions which transform a viscoelastic fluid into a viscoelastic solid during which the temperature, the chemistry and the mechanics are coupled. Part I of this work will deal with an isothermal viscoelastic formulation including shrinkage effects whereas the following Part II will give emphasis on the thermomechanical coupled approach. Some representative numerical examples conclude the paper and show the capability of the newly proposed constitutive formulation to capture major phenomena observed during the curing processes of polymers.

  14. Effect of hydrostatic pressure, temperature, and solvent on the rate of the Diels-Alder reaction between 9,10-anthracenedimethanol and maleic anhydride

    Science.gov (United States)

    Kiselev, V. D.; Kornilov, D. A.; Anikin, O. V.; Latypova, L. I.; Konovalov, A. I.

    2017-03-01

    The rate of the reaction between 9,10-anthracenedimethanol and maleic anhydride in 1,4-dioxane, acetonitrile, trichloromethane, and toluene is studied at 25, 35, 45°C in the pressure range of 1-1772 bar. The rate constants, enthalpies, entropies and activation volumes are determined. It is shown that the rate of reaction with 9,10-anthracenedimethanol is approximately one order of magnitude higher than with 9-anthracenemethanol.

  15. N-甲酰-L-天冬氨酸酐的合成%Synthesis of N-Formyl-L-aspartic Anhydride

    Institute of Scientific and Technical Information of China (English)

    冷一欣; 芮新生; 马江权; 孙豪义; 周宏斌

    2001-01-01

    N-Formyl-L-aspartic anhydride was prepared by the reaction of L-aspartic acid and formic acid with magnesium oxide catalyst in acetic anhydride solvent.Effects of temperature,operation time and molar ratio of formic acid and acetic anhydride were discussed.The optimum operation conditions were temperature 50 ℃,operation time 5 h, molar ratio of formic acid to L-aspartic acid 1.6∶1.0 and molar ratio of acetic anhydride to L-aspartic acid 2.3∶1.0.The yield was 90.35%.%在乙酸酐溶剂中,以氧化镁为催化剂,L-天冬氨酸与甲酸进行甲酰化反应并脱水生成N-甲酰-L-天冬氨酸酐。考察了温度、时间、甲酸和乙酸酐用量比对反应的影响,得到了优化的反应条件为:反应温度50 ℃,反应时间5 h,甲酸与L-天冬氨酸的物质的量比为1.6∶1.0,乙酸酐与L-天冬氨酸的物质的量比为2.3∶1.0,此时产物收率达90.35%。

  16. Synthesis and Characterization of Styrene- Ethylene-Propylene-Styrene (SEPS Grafted with Maleic Anhydride (MAH for Use as Coupling Agent in Wood Polymer Composite

    Directory of Open Access Journals (Sweden)

    M. Acevedo-Morantes

    2015-10-01

    Full Text Available Styrene-Ethylene-Propylene-Styrene (SEPS block copolymer was grafted with maleic anhydride (MAH by reactive extrusion (SEPS-g-MAH using an organic peroxide as initiator in the grafting. SEPS-g-MAH was synthesized for use as coupling agent in wood polymer composite (WPC. Identification of this compatibilizer was made using Fourier transform infrared spectroscopy (FTIR and the grafting degree was determinate with titration. The characteristic peaks in FTIR analysis indicated the presence of MAH in the copolymer.

  17. Synthesis of high molecular weight polylactic acid from aqueous lactic acid co-catalyzed by tin(II)chloride dihydrate and succinic anhydride

    Institute of Scientific and Technical Information of China (English)

    LEI Ziqiang; BAI Yanbin; WANG Shoufeng

    2005-01-01

    Polylactic acid was synthesized from commercial available cheap aqueous lactic acid (85%―90% w/w) using succinic anhydride and SnCl2·2H2O as catalyst in the absence of organic solvents. As a result, polylactic acid with a molecular weight of 60000 was prepared in 10 h. The new procedure is much simple, cheap and outstanding in that the start material is aqueous lactic acid; the catalytic system is environmentally benign.

  18. STUDY OF CARBONYLATION OF METHANOL TO ACETIC ACID AND ACETIC ANHYDRIDE OVER A BIDENTATE POLYMER BOUND CIS-DICARBONYLRHODIUM COMPLEX AS CATALYST

    Institute of Scientific and Technical Information of China (English)

    WANG Xiaojun; LIU Zhongyang; PAN Pinglai; YUAN Guoqing

    1996-01-01

    Copolymer of 2-vinylpyridine and vinylacetate coordinated with dicarbonylrhodium used as a catalyst for carbonylation of methanol to acetic acid and anhydride has been studied. The structural characteristics of the copolymer ligand and complex, and the influences of the reaction conditions on the carbonylation catalyzed by this polymer complex have been investigated. In comparison with small molecule catalyst of Rh complex, the bidentate copolymer coordinated complex has better thermal stability. The reaction mechanism of the carbonylation reaction is also illustrated.

  19. UV-cured methacrylic-silica hybrids: Effect of oxygen inhibition on photo-curing kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Corcione, C. Esposito; Striani, R.; Frigione, M., E-mail: mariaenrica.frigione@unisalento.it

    2014-01-20

    Highlights: • The kinetic behavior of novel photopolymerizable organic–inorganic hybrid system was studied as a function of the composition and of the atmosphere for reactions. • The UV-curing reaction of the hybrid mixture was found fast and complete. • The combined presence of thiol monomer and nanostructured silica allows to reduce the effect of inhibition of oxygen towards the radical photopolymerization. - Abstract: The kinetic behavior of innovative photopolymerizable UV-cured methacrylic–silica hybrid formulations, previously developed, was studied and compared to that of a reference control system. The organic–inorganic (O–I) hybrids proposed in this study are obtained from organic precursors with a high siloxane content mixed with tetraethoxysilane (TEOS) in such a way to produce co-continuous silica nano-domains dispersed within a cross-linked organic phase, as a result of the hydrolysis and condensation reactions. The kinetics of the radical photopolymerization mechanism induced by UV-radiations, in presence of a suitable photoinitiator, was studied by calorimetric, FTIR and Raman spectroscopic analyses, by varying the composition of the mixtures and the atmosphere for reactions. The well known effect of oxygen on the kinetic mechanism of the free radical photopolymerization of the methacrylic–siloxane based monomers was found to be strongly reduced in the hybrid system, especially when a proper thiol was used. The experimental calorimetric data were fitted using a simple kinetic model for radical photopolymerization reactions, obtaining a good agreement between the experimental data and the theoretical model. From the comparison of the kinetic constants calculated for control and hybrid systems, it was possible to assess the effect of the composition, as well as of the atmosphere used during the photo-polymerization process, on the kinetic of photopolymerization reaction.

  20. 聚乙烯接枝马来酸酐的工业生产技术研究%Production Technology of Polyethylene Grafted Maleic Anhydride

    Institute of Scientific and Technical Information of China (English)

    王益龙; 陈常明; 沈千新; 刘兴国

    2001-01-01

    Various methods of production of polyethylene grafted maleic anhydride (PE-g-MA) were compared by experiments. It was noted that the best way is reactive extrusion by means of reactive extruder. Its outstanding characteristics is that less free maleic anhydride exists in PE-g-MA and the process is automatic.It was also found that graft of HDPE was easier than that of LDPE,dicumyl peroxide had greater effect on graft rate than that of maleic anhydride.%通过实验比较了各种聚乙烯接枝马来酸酐的方法,发现利用反应式挤出机接枝最为理想,该方法的突出特点是产品中含游离态的马来酸酐少,工艺自动化及工作环境好等。通过实验还发现,HDPE比LDPE更易于接枝,接枝过程中过氧化物用量对接枝率的影响比MA用量对接枝率的影响大。

  1. Butanol Alcoholysis of Succinic Anhydride Under Neutral Condition%中性条件下丁二酸酐的丁醇解

    Institute of Scientific and Technical Information of China (English)

    高艳萍; 张利萍

    2011-01-01

    Alcoholysis of succinic anhydride and n - butyl alcohol takes place without catalysts and the monobutyl succinie forms. The IR and MS spectra of the products are measured respectively. The factors such as the molar radio between succinic anhydride and n - butanol, raction time are discussed. The radio of succinic acid to n - butanol is 1:3 ,the reaction time is 2h, alcoholysis radio is up to 95.8% ;the reaction time is over 2.5h,succinic anhydride has been alcoholyzed and a little amount of dibutyl has formed.%丁二酸酐和正丁醇在无催化剂参与下,直接醇解生成丁二酸正丁单酯。用IR谱和MS谱分别对产物进行了结构表征。反应讨论了物质的量比、反应时间对醇解反应的影响。当酸酐与醇的物质的量比为1:3,反应2h时,酸酐醇解率已达到95.8%;反应2.5h以上时,酸酐完全醇解,并且有少量丁二酸二丁酯生成。

  2. SENSORY CHARACTERISTICS OF NATIVE CHICKEN QUEEN PINEAPPLE-CURED HAM

    Directory of Open Access Journals (Sweden)

    Dr. Lilibeth A. Roxas

    2015-01-01

    Full Text Available The potential of Native Chicken to be processed into palatable ham was conducted making use of Queen Pineapple (QP crude extract as one of the curing ingredients. Primarily, the main goal is to develop a protocol in the manufacture of processed native chicken ham and determine the organoleptic quality of native chicken ham product. The age of the bird and maturity of the fruit were considered for the best organoleptic quality of chicken ham. In this study, the combine injection and dry cure (CIDC method of the conventional formula was adopted. The desired amount of QP crude extract was first determined for the pump pickle. Curing salt was used for the control while different volume of pineapple crude extract was used in two treatments. The protocols for processing native chicken were developed using slaughter native chicken, and QP crude extract as curing ingredient for ham making. Color, flavor, juiciness and tenderness were among the desirable characteristics considered in this study. The sensory evaluation by trained panelists on QP-cured ham samples demonstrated comparable results. All the cooked meat samples were apparently acceptable to the sensory panel. The mean scores for flavor, juiciness and tenderness of meat samples have slight differences; however, they are not statistically significant. Indeed, native chicken can be processed into palatable ham with queen pineapple (Formosa variety extract that served as curing ingredient, flavor enhancer and tenderizer. Native Chicken QP-Cured ham is a commendable value-added product for both native chicken and queen pineapple by-products (butterball size.

  3. Influence of argon laser curing on resin bond strength.

    Science.gov (United States)

    Hinoura, K; Miyazaki, M; Onose, H

    1993-04-01

    Light cured resin composites are usually cured with halogen lamps whose light output decreases with time and distance to the resin surface. This study compared bond strengths of resins to tooth structure cured with either an argon laser or a conventional halogen light. The enamel and dentin of bovine incisors were ground on the buccal surface with wet #600 grit SiC paper. A 4 x 2 mm mold was placed on the tooth surface and Scotchbond 2/Silux and Clearfil Photobond/Photo Clearfil A were placed into the molds and cured using a Quick Light or an argon laser for exposure times of 10, 20, and 30 seconds, and distances of 0.0, 0.5, 1.0, and 1.5 mm from the resin surface. The intensity of the Quick Light was measured as 510 mW/cm2 at 470 +/- 15 nm and the intensity of the argon laser was adjusted to 510 mW/cm2 before curing. Shear bond tests at a crosshead speed of 1.0 mm/min were performed after 24 hours of storage in water. The bond strengths obtained with the halogen lamp and the laser were not significantly different at the same exposure times and at 0.0 or 0.5 mm from the resin surface. The laser cured bond strengths did not decrease with increasing distance whereas there was a significant decrease in halogen bond strengths at distances greater than 0.5 mm for both resins. The use of the laser might provide a clinical advantage in cases where the curing light source cannot be brought into proximity to the surface of the resin.

  4. Preparation and Properties of PU Modified E-51/MeTHPA%聚氨酯改性E-51/MeTHPA的工艺与性能

    Institute of Scientific and Technical Information of China (English)

    于在乾; 冯文平; 张龙

    2012-01-01

    polyurethane (PU) grafted diglycidyl ether of bisphenol-A (DGEBA) and interpenetrating polymer network (PU/DGEBA IPN) were synthesized via solventless preparation and cured by liquid anhydride. The impact strength, dynamic mechanical properties, morphology and thermal gravity loss were investigated. The results indicate that the impact strength increases by 100% than of virgin DGEBA when PU content is 38 phr. PU/E-51 IPN structure shows 20% higher of the impact strength than PU grafted E-51 with the same PU content. SEM figure shows the distinct difference between PU grafted DGEBA and PU/DGEBA IPN. The mass loss of DGEBA modified by PAPI is 0.7 % at 280℃, which is approximate to that of virgin epoxy.%本体法制备了聚氨酯接枝及互穿网络改性环氧树脂,研究了酸酐为固化荆的条件下,制备工艺及聚合物结构对聚氨酯(PU)改性E-51环氧树脂(EP)性能的影响。实验确定了异氰酸酯的官能度、聚丙二醇(PPG)的分子量及聚氨酯懒聚体含量等对改性产物冲击强度、微观形貌及热性能的影响。结果表明,改性材料冲击强度随PPG分子量的增高而增大;互穿网络(IPN)结构改性E.51的抗冲击性能优于接枝改性,冲击断裂面上阻碍裂纹发展的点明显多于后者;支化PU改性E-51热稳定性高于线形PU改性,280℃热失重接近未改性环氧树脂。

  5. Radiation grafting of styrene and maleic anhydride onto PTFE membranes and sequent sulfonation for applications of vanadium redox battery

    Energy Technology Data Exchange (ETDEWEB)

    Qiu Jingyi; Ni Jiangfeng [Beijing National Laboratory for Molecular Science, Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Zhai Maolin [Beijing National Laboratory for Molecular Science, Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)], E-mail: mlzhai@pku.edu.cn; Peng Jing [Beijing National Laboratory for Molecular Science, Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Zhou Henghui [Beijing National Laboratory for Molecular Science, Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)], E-mail: hhzhou@pku.edu.cn; Li Jiuqiang; Wei Genshuan [Beijing National Laboratory for Molecular Science, Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

    2007-11-15

    Using {gamma}-radiation technique, poly(tetrafluoroethylene) (PTFE) membrane was grafted with styrene (St) (PTFE-graft-PS) or binary monomers of St and maleic anhydride (MAn) (PTFE-graft-PS-co-PMAn), respectively. Then grafted membranes were further sulfonated with chlorosulfonic acid into ion-exchange membranes (denoted as PTFE-graft-PSSA and PTFE-graft-PSSA-co-PMAc, respectively) for application of vanadium redox battery (VRB). Micro-FTIR analysis indicated that PTFE was successfully grafted and sulfonated at the above two different conditions. However, a higher degree of grafting (DOG) was obtained in St/MAn binary system at the same dose due to a synergistic effect. Comparing with PTFE-graft-PSSA, PTFE-graft-PSSA-co-PMAc membrane showed higher water uptake and ion-exchange capacity (IEC) and lower area resistance (AR) at the same DOG. In addition, PTFE-graft-PSSA-co-PMAc with 6% DOG also showed a higher IEC and higher conductivity compared to Nafion membrane. Radiation grafting of PTFE in St/MAn binary system and sequent sulfonation is an appropriate method for preparing ion-exchange membrane of VRB.

  6. Anhydride-functional silane immobilized onto titanium surfaces induces osteoblast cell differentiation and reduces bacterial adhesion and biofilm formation

    Energy Technology Data Exchange (ETDEWEB)

    Godoy-Gallardo, Maria, E-mail: maria.godoy.gallardo@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Guillem-Marti, Jordi, E-mail: jordi.guillem.marti@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Sevilla, Pablo, E-mail: psevilla@euss.es [Department of Mechanics, Escola Universitària Salesiana de Sarrià (EUSS), C/ Passeig de Sant Bosco, 42, 08017 Barcelona (Spain); Manero, José M., E-mail: jose.maria.manero@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Gil, Francisco J., E-mail: francesc.xavier.gil@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); and others

    2016-02-01

    Bacterial infection in dental implants along with osseointegration failure usually leads to loss of the device. Bioactive molecules with antibacterial properties can be attached to titanium surfaces with anchoring molecules such as silanes, preventing biofilm formation and improving osseointegration. Properties of silanes as molecular binders have been thoroughly studied, but research on the biological effects of these coatings is scarce. The aim of the present study was to determine the in vitro cell response and antibacterial effects of triethoxysilypropyl succinic anhydride (TESPSA) silane anchored on titanium surfaces. X-ray photoelectron spectroscopy confirmed a successful silanization. The silanized surfaces showed no cytotoxic effects. Gene expression analyses of Sarcoma Osteogenic (SaOS-2) osteoblast-like cells cultured on TESPSA silanized surfaces reported a remarkable increase of biochemical markers related to induction of osteoblastic cell differentiation. A manifest decrease of bacterial adhesion and biofilm formation at early stages was observed on treated substrates, while favoring cell adhesion and spreading in bacteria–cell co-cultures. Surfaces treated with TESPSA could enhance a biological sealing on implant surfaces against bacteria colonization of underlying tissues. Furthermore, it can be an effective anchoring platform of biomolecules on titanium surfaces with improved osteoblastic differentiation and antibacterial properties. - Highlights: • TESPSA silane induces osteoblast differentiation. • TESPSA reduces bacterial adhesion and biofilm formation. • TESPSA is a promising anchoring platform of biomolecules onto titanium.

  7. GRAFTING OF PEROXIDE-INITIATED MALEIC ANHYDRIDE ON SPHERICAL PE/PP IN-REACTOR BLEND GRANULES

    Institute of Scientific and Technical Information of China (English)

    Yan-zhong Zhang; Zhi-qiang Fan; Bai-geng Wu; Jun-ting Xu; Qi Wang

    2004-01-01

    Spherical polyethylene/polypropylene (PE/PP) in-reactor blend granules with various ethylene/propylene molar ratios and high porosity were synthesized using a high yield TiCl4/MgCl2 supported catalyst. A solution of benzoyl peroxide (BPO)/maleic anhydride (MAH)/xylene (interfacial reagent) or BPO/MAH/St (comonomer) was absorbed onto the PE/PP inreactor blend granules, and solid phase graft polymerization of MAH on PE/PP was conducted. The amount of grafted MAH on PE/PP was measured through chemical titration. The results showed that solid phase graft polymerization of MAH in PE/PP in-reactor blend granules produced graft copolymer with high amount of grafted MAH, and the amount of grafted MAH was raised slightly when St was introduced as comonomer. The graft in-reactor blend was fractionated into five fractions through temperature-gradient extraction fractionation (TGEF), and the fractions were analyzed by FTIR. The results revealed that MAH is mainly grafted on the PE segments, whereas MAH was predominantly grafted on the PP segments when St was present in the graft polymerization system. In addition, the final product is still in the form of regular spherical granules, which is beneficial for industrial processing.

  8. Development of a guided bone regeneration device using salicylic acid-poly(anhydride-ester) polymers and osteoconductive scaffolds.

    Science.gov (United States)

    Mitchell, Ashley; Kim, Brian; Cottrell, Jessica; Snyder, Sabrina; Witek, Lukasz; Ricci, John; Uhrich, Kathryn E; O'Connor, J Patrick

    2014-03-01

    Successful repair of craniofacial and periodontal tissue defects ideally involves a combined therapy that includes inflammation modulation, control of soft tissue infiltration, and bone regeneration. In this study, an anti-inflammatory polymer, salicylic acid-based poly(anhydride-ester) (SAPAE) and a three-dimensional osteoconductive ceramic scaffold were evaluated as a combined guided bone regeneration (GBR) system for concurrent control of inflammation, soft tissue ingrowth, and bone repair in a rabbit cranial defect model. At time periods of 1, 3, and 8 weeks, five groups were compared: (1) scaffolds with a solid ceramic cap (as a GBR structure); (2) scaffolds with no cap; (3) scaffolds with a poly(lactide-glycolide) cap; (4) scaffolds with a slow release SAPAE polymer cap; and (5) scaffolds with a fast release SAPAE polymer cap. Cellular infiltration and bone formation in these scaffolds were evaluated to assess inflammation and bone repair capacity of the test groups. The SAPAE polymers suppressed inflammation and displayed no deleterious effect on bone formation. Additional work is warranted to optimize the anti-inflammatory action of the SAPAE, GBR suppression of soft tissue infiltration, and stimulation of bone formation in the scaffolds and create a composite device for successful repair of craniofacial and periodontal tissue defects.

  9. In vitro release of clomipramine HCl and buprenorphine HCl from poly adipic anhydride (PAA) and poly trimethylene carbonate (PTMC) blends.

    Science.gov (United States)

    Dinarvand, Rassoul; Alimorad, Mohammed Massoud; Amanlou, Massoud; Akbari, Hamid

    2005-10-01

    Controlled drug-delivery technology is concerned with the systematic release of a pharmaceutical agent to maintain a therapeutic level of the drug in the body for modulated and/or prolonged periods of time. This may be achieved by incorporating the therapeutic agent into a degradable polymer vehicle, which releases the agent continuously as the matrix erodes. In this study, poly trimethylene carbonate (PTMC), an aliphatic polycarbonate, and poly adipic anhydride (PAA), an aliphatic polyanhydride, were synthesized via melt condensation and ring-opening polymerization of trimethylene carbonate and adipic acid, respectively. The release of clomipramine HCl and buprenorphine HCl from discs prepared with the use of PTMC-PAA blends in phosphate buffer (pH 7.4) are also described. Clomipramine HCl and buprenorphine HCl were both used as hydrophilic drug models. Theoretical treatment of the data with the Peppas model revealed that release of clomipramine HCl (5%) in devices containing 70% PTMC or more followed a Fickian diffusion model. However, the releases of buprenorphine HCl (5%) in the same devices were anomalous. For devices containing 50% and more PAA, surface erosion may play a significant role in the release of both molecules.

  10. Olefin-maleic-anhydride copolymer based additives: a novel approach for compatibilizing blends of waste polyethylene and crumb rubber.

    Science.gov (United States)

    Tóth, Balázs; Varga, Csilla; Bartha, László

    2015-04-01

    In our work processing conditions and mechanical properties of waste polyethylene (PE)/crumb rubber (CR) blends have been improved by new types of compatibilizing additives synthesized from experimental olefin-maleic-anhydride copolymers at our laboratory. Compatibilizing additives have been introduced into the PE/CR blends in 0.2 wt% while CR concentration has been varied between 10 and 50 wt%. For comparison of the effects commercially available MA-g-PO type compatibilizing additives have also been applied. Tensile and Charpy impact tests of the compression moulded samples have been carried out. Several experimental additives have enhanced properties of the PE/CR blends either from the point of view of tensile or Charpy impact strength while commercial additives have had improving effects only on one of the abovementioned mechanical properties but not for both of them simultaneously. Since good mechanical properties could be achieved by our experimental compatibilizers good adhesion in the waste PE/CR samples have been considered and was proven by SEM graphs either.

  11. Separator Membrane from Crosslinked Poly(Vinyl Alcohol and Poly(Methyl Vinyl Ether-alt-Maleic Anhydride

    Directory of Open Access Journals (Sweden)

    Charu Vashisth Rohatgi

    2015-03-01

    Full Text Available In this work, we report separator membranes from crosslinking of two polymers, such as poly vinyl alcohol (PVA with an ionic polymer poly(methyl vinyl ether-alt-maleic anhydride (PMVE-MA. Such interpolymer-networked systems were extensively used for biomedical and desalination applications but they were not examined for their potential use as membranes or separators for batteries. Therefore, the chemical interactions between these two polymers and the influence of such crosslinking on physicochemical properties of the membrane are systematically investigated through rheology and by critical gel point study. The hydrogen bonding and the chemical interaction between PMVE-MA and PVA resulted in highly cross-linked membranes. Effect of the molecular weight of PVA on the membrane properties was also examined. The developed membranes were extensively characterized by studying their physicochemical properties (water uptake, swelling ratio, and conductivity, thermal and electrochemical properties using differential scanning calorimetry (DSC, dynamic mechanical analysis (DMA, thermo-gravimetric analysis (TGA and electrochemical impedance spectroscopy (EIS. The DSC study shows the presence of a single Tg in the membranes indicating compatibility of the two polymers in flexible and transparent films. The membranes show good stability and ion conductivity suitable for separator applications.

  12. Preparation, characterization and luminescent properties of dense nano-silica hybrids loaded with 1,8-naphthalic anhydride.

    Science.gov (United States)

    Wang, Jinpeng; Sun, Jihong; Li, Yuzhen; Wang, Feng

    2014-03-01

    Novel luminescent dense nano-silica hybrid materials (DNSS) modified with different amounts of (3-aminopropyl)triethoxysilane (APTES) and 1,8-naphthalic anhydride (NA) were successfully synthesized via two steps combined with post-grafting methods. Powder X-ray diffraction (XRD), N2-sorption analysis, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), photoluminescence (PL) spectroscopy and elemental analysis, as well as time-resolved decays were employed to characterize the resultant hybrid materials. The results revealed that luminescent organic molecules had been successfully loaded onto the amine-modified surface of nano-silica spheres. In addition, their fluorescence intensity and characteristic peak of emission spectra changed with increasing amount of APTES and NA additive. In particular, the characteristic peak showed a red shift from 390 to 450 nm, however, this was inconsistent with results calculated on the basis of the elemental analysis data, most probably because of the dispersion behaviors of NA molecules from the aggregating to the monolayer state. These observations demonstrated the existence of a quantum confinement effectiveness of NA-DNSS samples, and therefore a possible mechanism was put forward.

  13. Intranasal Administration of Maleic Anhydride-Modified Human Serum Albumin for Pre-Exposure Prophylaxis of Respiratory Syncytial Virus Infection

    Directory of Open Access Journals (Sweden)

    Zhiwu Sun

    2015-02-01

    Full Text Available Respiratory syncytial virus (RSV is the leading cause of pediatric viral respiratory tract infections. Neither vaccine nor effective antiviral therapy is available to prevent and treat RSV infection. Palivizumab, a humanized monoclonal antibody, is the only product approved to prevent serious RSV infection, but its high cost is prohibitive in low-income countries. Here, we aimed to identify an effective, safe, and affordable antiviral agent for pre-exposure prophylaxis (PrEP of RSV infection in children at high risk. We found that maleic anhydride (ML-modified human serum albumin (HSA, designated ML-HSA, exhibited potent antiviral activity against RSV and that the percentages of the modified lysines and arginies in ML- are correlated with such anti-RSV activity. ML-HSA inhibited RSV entry and replication by interacting with viral G protein and blocking RSV attachment to the target cells, while ML-HAS neither bound to F protein, nor inhibited F protein-mediated membrane fusion. Intranasal administration of ML-HSA before RSV infection resulted in significant decrease of the viral titers in the lungs of mice. ML-HSA shows promise for further development into an effective, safe, affordable, and easy-to-use intranasal regimen for pre-exposure prophylaxis of RSV infection in children at high risk in both low- and high-income countries.

  14. Investigation of diode parameters using – and – characteristics of Al/maleic anhydride (MA)/p-Si structure

    Indian Academy of Sciences (India)

    A B Selçuk; S Bilge Ocak; G Kahraman; A H Selçuk

    2014-12-01

    Al/maleic anhydride (MA)/p-Si metal–polymer–semiconductor (MPS) structures were prepared on p-Si substrate by spin coating. Device parameters of Al/MA/p-Si structure have been determined by means of capacitance–voltage (–) and conductance–voltage (–) measurements between 700 kHz and 1.5 MHz and current–voltage (–) measurements at 300 K. The parameters of diode such as the ideality factor, series resistance, barrier height (BH) and flat band barrier height were calculated from the forward bias – characteristics. The investigation of interface states that density and series resistance from – and – characteristics in Al/MA/p-Si device has been reported. The frequency dependence of the capacitance could be attributed to trapping states. Several important device parameters such as the BH $\\phi_{b}$, fermi energy ($E_{F}$), diffusion voltage ($V_{D}$), donor carrier concentration ($N_{D}$) and space charge layer width ($W_{D}$) for the device have been obtained between 700 kHz and 1.5 MHz. The –, –- and –- characteristics confirm that the parameters like the BH, interface state density (it) and series resistance ($R_{s}$) of the diode are strongly dependent on the electrical parameters in the MPS structures.

  15. Using monosaccharide anhydrides to estimate the impact of wood combustion on fine particles in the Helsinki Metropolitan Area

    Energy Technology Data Exchange (ETDEWEB)

    Saarnio, K.; Saarikoski, S. [Finnish Meteorological Institute, Helsinki (Finland); Niemi, J.V. [HSY Helsinki Region Environmental Services Authority, Helsinki (Finland)

    2012-11-01

    The spatiotemporal variation of ambient particles under the influence of biomass burning emissions was studied in the Helsinki Metropolitan Area (HMA) in selected periods during 2005-2009. Monosaccharide anhydrides (MAs; levoglucosan, mannosan and galactosan), commonly known biomass burning tracers, were used to estimate the wood combustion contribution to local particulate matter (PM) concentration levels at three urban background sites close to the city centre, and at three suburban sites influenced by local small-scale wood combustion. In the cold season (October-March), the mean MAs concentrations were 115-225 ng m{sup -3} and 83-98 ng m{sup -} {sup 3}at the suburban and urban sites, respectively. In the warm season, the mean MAs concentrations were low (19-78 ng m{sup -3}), excluding open land fire smoke episodes (222-378 ng m{sup -}3{sup )}. Regionally distributed wood combustion particles raised the levels over the whole HMA while particles from local wood combustion sources raised the level at suburban sites only. The estimated average contribution of wood combustion to fine particles (PM{sub 2.5}) ranged from 18% to 29% at the urban sites and from 31% to 66% at the suburban sites in the cold season. The PM measurements from ambient air and combustion experiments showed that the proportions of the three MAs can be utilised to separate the wildfire particles from residential wood combustion particles. (orig.)

  16. In Vivo Evaluation of Nerve Guidance Conduits Comprised of a Salicylic Acid-based Poly(anhydride-ester) Blend

    Science.gov (United States)

    Lee, Yong Soo

    Unlike the central nervous system, peripheral nervous system can regenerate from injury. However, without surgical intervention, the results are often poor. Autologous nerve grafting is the golden standard for repairing peripheral nerve injury; but limited donor availability and donor site morbidity led researchers to seek alternative methods. Among the many alternative treatment options, synthetic nerve guidance conduits (NGCs) have been most actively developed. The goal of NGCs is to serve as a physical scaffold that aids the axonal regeneration process while preventing scar tissue formation that interferes with regeneration. Biocompatible and biodegradable NGCs would provide additional benefits: minimize foreign body reaction and avoid secondary surgeries to remove NGCs. We developed a unique NGC that incorporated the characteristics described above and can release an anti-inflammatory drug, salicylic acid. In this work, in vivo assays were performed to evaluate NGCs fabricated from a poly(anhydride-ester) blend. To further assist in the regeneration process, bovine native collagen type I hydrogel were inserted into the NGCs lumen which was then implanted in femoral nerve of mice for up to 16 weeks. These studies demonstrated in vivo biodegradability, biocompatibility, and axonal regeneration following an injury to the peripheral nerve. These studies provide greater insights into the importance of designing NGCs and how they aid in regeneration and functional recovery of subjects.

  17. Adsorption of heavy metal ions and azo dyes by crosslinked nanochelating resins based on poly(methylmethacrylate-co-maleic anhydride

    Directory of Open Access Journals (Sweden)

    M. Ghaemy

    2014-03-01

    Full Text Available Chelating resins are suitable materials for the removal of heavy metals in water treatments. A copolymer, Poly(MMA-co-MA, was synthesized by radical polymerization of maleic anhydride (MA and methyl methacrylate (MMA, characterized and transformed into multifunctional nanochelating resin beads (80–150 nm via hydrolysis, grafting and crosslink reactions. The resin beads were characterized by swelling studies, field emission scanning electron microscopy (FESEM and Fourier transform infrared spectroscopy (FTIR. The main purpose of this work was to determine the adsorption capacity of the prepared resins (swelling ratio ~55% towards metal ions such as Hg2+, Cd2+, Cu2+ from water at three different pH values (3, 6 and 9. Variations in pH and types of metal ions have not significantly affected the chelation capacity of these resins. The maximum chelation capacity of one of the prepared resin beads (Co-g-AP3 for Hg2+ was 63, 85.8 and 71.14 mg/g at pH 3, 6 and 9, respectively. Approximately 96% of the metal ions could be desorbed from the resin. Adsorption capacity of these resins towards three commercial synthetic azo dyes was also investigated. The maximum adsorption of dye AY42 was 91% for the resin Co-g-AP3 at room temperature. This insures the applicability of the synthesized resins for industrial applications.

  18. Preparation of High Density Polyethylene/Waste Polyurethane Blends Compatibilized with Polyethylene-Graft-Maleic Anhydride by Radiation

    Directory of Open Access Journals (Sweden)

    Jong-Seok Park

    2015-04-01

    Full Text Available Polyurethane (PU is a very popular polymer that is used in a variety of applications due to its good mechanical, thermal, and chemical properties. However, PU recycling has received significant attention due to environmental issues. In this study, we developed a recycling method for waste PU that utilizes the radiation grafting technique. Grafting of waste PU was carried out using a radiation technique with polyethylene-graft-maleic anhydride (PE-g-MA. The PE-g-MA-grafted PU/high density polyethylene (HDPE composite was prepared by melt-blending at various concentrations (0–10 phr of PE-g-MA-grafted PU. The composites were characterized using fourier transform infrared spectroscopy (FT-IR, and their surface morphology and thermal/mechanical properties are reported. For 1 phr PU, the PU could be easily introduced to the HDPE during the melt processing in the blender after the radiation-induced grafting of PU with PE-g-MA. PE-g-MA was easily reacted with PU according to the increasing radiation dose and was located at the interface between the PU and the HDPE during the melt processing in the blender, which improved the interfacial interactions and the mechanical properties of the resultant composites. However, the elongation at break for a PU content >2 phr was drastically decreased.

  19. Photothermal radiometry monitoring of light curing in resins

    Energy Technology Data Exchange (ETDEWEB)

    Zambrano-Arjona, M A [Applied Physics Department, Cinvestav-Unidad Merida, A.P. 73 Cordemex, Merida, 97310 (Mexico); Medina-Esquivel, R [Cinvestav-Unidad Queretaro, Libramiento Norponiente 2000 Fracc. Real de Juriquilla, CP 76230, Queretaro (Mexico); Alvarado-Gil, J J [Applied Physics Department, Cinvestav-Unidad Merida, A.P. 73 Cordemex, Merida, 97310 (Mexico)

    2007-10-07

    Real time measurement of thermal diffusivity during the evolution of the light curing process in dental resins is reported using photothermal radiometry. The curing is induced by a non-modulated blue light beam, and at the same time, a modulated red laser beam is sent onto the sample, generating a train of thermal waves that produce modulated infrared radiation. The monitoring of this radiation permits to follow the time evolution of the process. The methodology is applied to two different commercially available light curing resin-based composites. In all cases thermal diffusivity follows a first order kinetics with similar stabilization characteristic times. Analysis of this kinetics permits to exhibit the close relationship of increase in thermal diffusivity with the decrease in monomer concentration and extension of the polymerization in the resin, induced by the curing light. It is also shown that the configuration in which the resin is illuminated by the modulated laser can be the basis for the development of an in situ technique for the determination of the degree of curing.

  20. Caul and method for bonding and curing intricate composite structures

    Science.gov (United States)

    Willden, Kurtis S. (Inventor); Goodno, Kenneth N. (Inventor)

    1993-01-01

    The invention disclosed here is a method for forming and curing an intricate structure of criss-crossing composite stringers and frames that are bonded to a skin panel. A structure constructed in accordance with the invention would be well-suited for use as a portion of an aircraft fuselage, a boat hull, or the like. The method is preferably practiced by applying uncured composite stringers to an uncured composite sheet panel. This is followed by placing cured frames crosswise over the stringers. The frames have openings at the locations where they intersect with the stringers which enables the frames to come into direct contact with the skin along most of their length. During the forming and curing process, the stringers are covered with a plurality of cauls, and the entire assembly of skin panel, stringers, frames and cauls is subjected to a vacuum bagging and curing process. The cauls serve to maintain both part shape and to control the flow of resin within the stringers as they are cured. Further, they probably eliminate the need for intermediate protective materials between the vacuum bag and the stringers.

  1. Fiber-Matrix Interface Studies on Electron Beam Cured Composites

    Energy Technology Data Exchange (ETDEWEB)

    Drazel, L.T.; Janke, C.J.; Yarborough, K.D.

    1999-05-23

    The recently completed Department of Energy (DOE) and industry sponsored Cooperative Research and Development Agreement (CRADA) entitled, ''Electron Beam Curing of Polymer Matrix Composites,'' determined that the interlaminar shear strength properties of the best electron beam cured IM7/epoxy composites were 19-28% lower than autoclave cured IM7/epoxy composites (i.e. IM7/977-2 and IM7/977-3). Low interlaminar shear strength is widely acknowledged as the key barrier to the successful acceptance and implementation of electron beam cured composites in the aircraft/aerospace industry. The objective of this work was to improve the interlaminar shear strength properties of electron beam cured composites by formulating and evaluating several different fiber sizings or coating materials. The researchers have recently achieved some promising results by having discovered that the application of epoxy-based, electron beam compatible sizings or coatings onto surface-treated, unsized IM7 carbon fibers improved the composite interlaminar shear strength properties by as much as 55% versus composites fabricated from surface-treated, unsized IM7 fibers. In addition, by applying these same epoxy-based sizings or coatings onto surface-treated, unsized IM7 fibers it was possible to achieve an 11% increase in the composite interlaminar shear strength compared to composites made from surface-treated, GP-sized IM7 fibers. Work is continuing in this area of research to further improve these properties.

  2. Thermal stability and curing kinetics of polycarbosilane fibers

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Thermal stability and curing kinetics of polycarbosilane (PCS) fibers were studied by thermogravimetry (TG), Fourier transform infrared spectroscopy(FT-IR). Curing is an essential step in the preparation of SiC fibers and the properties of SiC fibers are affected greatly by curing conditions. TG measurement performed in air shows that mass gain starts at approximately 200℃ and PCS fibers are sensitive to oxygen. Curing with oxygen, which results in crosslinking on the surface, enabled PCS fibers to retain its shape during high-temperature pyrolysis. The curing of PCS fibers is oxidation of Si-H and Si-CH3, then Si-O-Si and Si-O-C bonds are formed. This is a first order reaction, with activation energy of 79.27 kJ/mol, and the pre-exponential factor is calculated as 3.07 × 106.The kinetics model was obtained and the experimental data of PCS fibers show good agreement with the kinetics model.

  3. Characterization of Moisture Diffusion in Cured Concrete Slabs at Early Ages

    OpenAIRE

    Xiao Zhang; Hongduo Zhao

    2015-01-01

    The objective of this paper is to investigate the characterization of moisture diffusion inside early-age concrete slabs subjected to curing. Time-dependent relative humidity (RH) distributions of three mixture proportions subjected to three different curing methods (i.e., air curing, water curing, and membrane-forming compounds curing) and sealed condition were measured for 28 days. A one-dimensional nonlinear moisture diffusion partial differential equation (PDE) based on Fick’s second law,...

  4. Prediction of 28-day Compressive Strength of Concrete from Early Strength and Accelerated Curing Parameters

    OpenAIRE

    T.R. Neelakantan; S. Ramasundaram; Shanmugavel, R.; R. Vinoth

    2013-01-01

    Predicting 28-day compressive strength of concrete is an important research task for many years. In this study, concrete specimens were cured in two phases, initially at room temperature for a maximum of 30 h and later at a higher temperature for accelerated curing for a maximum of 3 h. Using the early strength obtained after the two-phase curing and the curing parameters, regression equations were developed to predict the 28-day compressive strength. For the accelerated curing (higher temper...

  5. Comparative evaluation of surface porosities in conventional heat polymerized acrylic resin cured by water bath and microwave energy with microwavable acrylic resin cured by microwave energy

    Directory of Open Access Journals (Sweden)

    Sunint Singh

    2013-01-01

    Full Text Available Background: Conventional heat cure poly methyl methacrylate (PMMA is the most commonly used denture base resin despite having some short comings. Lengthy polymerization time being one of them and in order to overcome this fact microwave curing method was recommended. Unavailability of specially designed microwavable acrylic resin made it unpopular. Therefore, in this study, conventional heat cure PMMA was polymerized by microwave energy. Aim and Objectives: This study was designed to evaluate the surface porosities in PMMA cured by conventional water bath and microwave energy and compare it with microwavable acrylic resin cured by microwave energy. Materials and Methods: Wax samples were obtained by pouring molten wax into a metal mold of 25 mm × 12 mm × 3 mm dimensions. These samples were divided into three groups namely C, CM, and M. Group C denotes conventional heat cure PMMA cured by water bath method, CM denotes conventional heat cure PMMA cured by microwave energy, M denotes specially designed microwavable acrylic denture base resin cured by microwave energy. After polymerization, each sample was scanned in three pre-marked areas for surface porosities using the optical microscope. As per the literature available, this instrument is being used for the first time to measure the porosity in acrylic resin. It is a reliable method of measuring area of surface pores. Portion of the sample being scanned is displayed on the computer and with the help of software area of each pore was measured and data were analyzed. Results: Conventional heat cure PMMA samples cured by microwave energy showed maximum porosities than the samples cured by conventional water bath method and microwavable acrylic resin cured by microwave energy. Higher percentage of porosities was statistically significant, but well within the range to be clinically acceptable. Conclusion: Within the limitations of this in-vitro study, conventional heat cure PMMA can be cured by

  6. The effect of gamma radiation on the ageing of sulfur cured nr/csm and nbr/csm rubber blends reinforced by carbon black

    Directory of Open Access Journals (Sweden)

    Gordana Marković

    2009-10-01

    Full Text Available In this work the effect of the γ-radiation dose on ageing of carbon black reinforced elastomeric materials was studied. The compounds based on natural rubber/chlorosulfonated rubber blend (NR/CSM and butadiene acrylonitrile rubber/chlorosulfonated rubber blend (NBR/CSM (50:50, w/w with different loadings (0, 20, 40, 50, 60, 80 and 100 phr of the filler with the average particle size of 40 nm were cured by sulfur. The obtained elastomeric composites were subjected to radiation doses (100, 200, 300 and 400 kGy in the presence of oxygen. The changes of material mechanical properties were estimated after radiation accelerated ageing. By using Fourier transform infrared measurements (ATR-FTIR it was assessed that after exposure to doses of 100 kGy alcohols, ethers, lactones, anhydrides, esters and carboxylic acids are formed in materials. The formation of shorter polyene sequences and aromatic rings in aged samples are assumed on the basis of the obtained spectra.

  7. Influence of light curing units on failure of directcomposite restorations

    Directory of Open Access Journals (Sweden)

    Sameer Jadhav

    2011-01-01

    Full Text Available Light polymerizable tooth colored restorative materials are most widely preferred for advantages such as esthetics, improved physical properties and operator′s control over the working time. Since the introduction of these light polymerizable restorative materials, there has been a concern about the depth of appropriate cure throughout the restoration. Photopolymerization of the composite is of fundamental importance because adequate polymerization is a crucial factor for optimization of the physical and mechanical properties and clinical results of the composite material. Inadequate polymerization results in greater deterioration at the margins of the restoration, decreased bond strength between the tooth and the restoration, greater cytotoxicity, and reduced hardness. Therefore, the dentist must use a light curing unit that delivers adequate and sufficient energy to optimize composite polymerization. Varying light intensity affects the degree of conversion of monomer to polymer and depth of cure.

  8. Properties of high performance bisphenol F epoxy resin/anhydride curing system for VARTM%VARTM用高性能双酚F环氧/酸酐固化体系的性能

    Institute of Scientific and Technical Information of China (English)

    郭嘉琳; 袁象恺; 谢丹; 周金利; 姜正飞; 余木火

    2014-01-01

    采用示差扫描量热仪,力学性能测试,扫描电镜分析和热重分析研究了在双酚F环氧树脂/酸酐固化体系中加入纳米粒子型增韧剂的效果.并以加入纳米粒子增韧剂的树脂体系为基体,碳纤维平纹布为增强体,通过真空辅助树脂传递模塑(VARTM)工艺制备了复合材料,对其力学性能和微缺陷进行了研究.结果表明,加入纳米粒子型增韧剂后,在弯曲强度损失较小的情况下,浇注体的拉伸性能有所提高,冲击韧性大幅增加.制备的复合材料树脂/纤维浸润良好,没有干斑存在,微缺陷较少,力学性能优异,有望用于VARTM成型大型汽车结构部件的制造.

  9. 双酚-S环氧树脂与琥珀酸酐固化反应动力学%Kinetics of Succinic Anhydride Curing of Bisphenol-S Epoxy Resin

    Institute of Scientific and Technical Information of China (English)

    高俊刚; 李燕芳

    2000-01-01

    用差示扫描量热法(DSC)研究了双酚-S环氧树脂(BPSER)与琥珀酸酐固化反应的历程.实验结果表明,固化反应主要分两个阶段,前期由化学动力学控制,服从自催化机理.实验数据利用Kamal方程处理得到两个速率常数k1、k2及两个反应级数m、n.k1、k2的值随反应温度的升高呈增大的趋势,总反应级数m+n在2~2.5之间.当转化率达到40%左右后,由于交联程度增加,分子量迅速增长,分子间扩散较慢,进入反应的第二阶段,主要由扩散作用控制固化速率.

  10. Temperature and curing time affect composite sorption and solubility

    Directory of Open Access Journals (Sweden)

    Fabrício Luscino Alves de Castro

    2013-04-01

    Full Text Available Objective: This study evaluated the effect of temperature and curing time on composite sorption and solubility. Material and Methods: Seventy five specimens (8×2 mm were prepared using a commercial composite resin (ICE, SDI. Three temperatures (10°C, 25°C and 60°C and five curing times (5 s, 10 s, 20 s, 40 s and 60 s were evaluated. The specimens were weighed on an analytical balance three times: A: before storage (M1; B: 7 days after storage (M2; C: 7 days after storage plus 1 day of drying (M3. The storage solution consisted of 75% alcohol/25% water. Sorption and solubility were calculated using these three weights and specimen dimensions. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U Tests (α=5%. Results: The results showed that time, temperature and their interaction influenced the sorption and solubility of the composite (p0.05. The 60°C composite temperature led to lower values of sorption for all curing times when compared with the 10°C temperature (p0.05. Solubility was similar at 40 s and 60 s for all temperatures (p>0.05, but was higher at 10°C than at 60°C for all curing times (p0.05. Conclusions: In conclusion, higher temperatures or longer curing times led to lower sorption and solubility values for the composite tested; however, this trend was only significant in specific combinations of temperature and curing times.

  11. Grey Disorder in Field Flue—Cured Tobacco

    Institute of Scientific and Technical Information of China (English)

    ZHANGXIN; ZHAOQIBO; 等

    1999-01-01

    A field study was carried out on the grey disorder in flue-cured tobacco( Nicotiana tabacum L.) leaves.The results showed that low Eh and high available Fe content in the soils were responsible for the grey tobacco and dead roots.Grey disorder leaves produced low quality lamina,which was low in N,nicotine,reduced sugar and K contents,In this study,soil available Mn and leaf Mn contents were in a relatively low level and should not be an important factor in the occurrence of grey disorder in flue-cured tobacco.

  12. Magnetoactive elastomeric composites: Cure, tensile, electrical and magnetic properties

    Indian Academy of Sciences (India)

    K Sasikumar; G Suresh; K A Thomas; Reji John; V Natarajan; T Mukundan; R M R Vishnubhatla

    2006-11-01

    Magnetically active elastomer materials were prepared by incorporating nickel powder in synthetic elastomeric matrices, polychloroprene and nitrile rubber. Cure characteristics, mechanical, electrical and magnetic properties were experimentally determined for different volume fractions of magnetoactive filler. The cure time decreases sharply for initial filler loading and the decrease is marginal for additional loading of filler. The tensile strength and modulus at 100% strain was found to increase with increase in the volume fraction of nickel due to reinforcement action. The magnetic impedance and a.c. conductivity are found to increase with increase in volume fraction of nickel as well as frequency.

  13. Realtime 3D stress measurement in curing epoxy packaging

    DEFF Research Database (Denmark)

    Richter, Jacob; Hyldgård, A.; Birkelund, Karen;

    2007-01-01

    This paper presents a novel method to characterize stress in microsystem packaging. A circular p-type piezoresistor is implemented on a (001) silicon chip. We use the circular stress sensor to determine the packaging induced stress in a polystyrene tube filled with epoxy. The epoxy curing process...... is monitored by stress measurements. From the stress measurements we conclude that the epoxy cures in 8 hours at room temperature. We find the difference in in-plane normal stresses to be sigmaxx-sigmayy=6.7 MPa and (sigmaxx+sigmayy-0.4sigmazz)=232 MPa....

  14. Optimization of the curing process of a sandwich panel

    Science.gov (United States)

    Phyo Maung, Pyi; Tatarnikov, O.; Malysheva, G.

    2016-10-01

    This study presented finite element modelling and experimental measurements of temperatures during the autoclave curing of the T-50 aircraft wing sandwich panel. This panel consists of upper and lower carbon fibre based laminates and an aluminium foil honeycomb. The finite element modelling was performed using the Femap-Nastran product. During processing, the temperature at various points on the surface of the panel was measured using the thermocouples. The finite element method simulated the thermal conditions and determined the temperatures in the different parts of the panel for a full cycle of the curing process. A comparison of the calculated and experimental data shows that their difference does not exceed 6%.

  15. Preliminary toxicological study of Sylgard 184 curing agent

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D.M.; London, J.E.; Drake, G.A.; Thomas, R.G.

    1978-06-01

    The acute oral LD/sub 50//sup 30/ values for mice and rats receiving Sylgard 184 curing agent were greater than 5 g/kg. According to classical guidelines, the compound would be considered slightly toxic or practically nontoxic in both species. Skin application studies in the rabbit demonstrated the compound to be mildly irritating. Eye irritation studies, also in the rabbit, showed that Sylgard 184 curing agent was a mild but transitory irritant. The sensitization study in guinea pigs did not show the resin to be deleterious.

  16. Emergent Cure Chemistry in the Development of Aerospace Materials

    Science.gov (United States)

    2015-03-25

    R4 R3-SHR3-S-CH2-CH2-R4Product Anti-Markovnikov • Thiol-ene chemistry is a hybrid of free radical and condensation chemistry . It combines the speed...Charts 3. DATES COVERED (From - To) March 2015-March 2015 4. TITLE AND SUBTITLE Emergent cure chemistry in the development of aerospace materials...cure chemistry in the development of aerospace materials Joseph M. Mabry, Ph.D. Air Force Research Laboratory joseph.mabry@us.af.mil (661) 275-5857

  17. Effects of feeding high protein or conventional canola meal on dry cured and conventionally cured bacon.

    Science.gov (United States)

    Little, K L; Bohrer, B M; Stein, H H; Boler, D D

    2015-05-01

    Objectives were to compare belly, bacon processing, bacon slice, and sensory characteristics from pigs fed high protein canola meal (CM-HP) or conventional canola meal (CM-CV). Soybean meal was replaced with 0 (control), 33, 66, or 100% of both types of canola meal. Left side bellies from 70 carcasses were randomly assigned to conventional or dry cure treatment and matching right side bellies were assigned the opposite treatment. Secondary objectives were to test the existence of bilateral symmetry on fresh belly characteristics and fatty acid profiles of right and left side bellies originating from the same carcass. Bellies from pigs fed CM-HP were slightly lighter and thinner than bellies from pigs fed CM-CV, yet bacon processing, bacon slice, and sensory characteristics were unaffected by dietary treatment and did not differ from the control. Furthermore, testing the existence of bilateral symmetry on fresh belly characteristics revealed that bellies originating from the right side of the carcasses were slightly (P≤0.05) wider, thicker, heavier and firmer than bellies from the left side of the carcass.

  18. Volatile compounds of dry-cured Iberian ham as affected by the length of the curing process.

    Science.gov (United States)

    Ruiz, J; Ventanas, J; Cava, R; Andrés, A; García, C

    1999-05-01

    Volatile compounds from 10 dry-cured Iberian hams ripened for two different processing times, a prolonged traditional one (600 days) and a shortened process (420 days), were analysed by purge and trap coupled to gas chromatography-mass spectroscopy. Eighty-three compounds were identified which agreed with the major classes found in other ham types. The amount of methyl branched alkanes was much higher than in other dry-cured ham types, probably due to the feeding regime. The percentages of 2- and 3-methylbutanal were higher (p<0.0001 and p<0.0003, respectively) in the longer aged hams, whereas the amounts of some compounds from lipid oxidation decreased from 420 to 600 days aging. In agreement with these observations, 600-day hams had higher scores for those odour and flavour traits usually considered to be positive attributes and lower scores for rancidity. A positive and significant correlation between 2-methyl butanal and cured flavour was found.

  19. Evaluation of methods for measuring relative permeability of anhydride from the Salado Formation: Sensitivity analysis and data reduction

    Energy Technology Data Exchange (ETDEWEB)

    Christiansen, R.L.; Kalbus, J.S. [Colorado School of Mines, Golden, CO (United States). Petroleum Engineering Dept.; Howarth, S.M. [Sandia National Labs., Albuquerque, NM (United States)

    1997-05-01

    This report documents, demonstrates, evaluates, and provides theoretical justification for methods used to convert experimental data into relative permeability relationships. The report facilities accurate determination of relative permeabilities of anhydride rock samples from the Salado Formation at the Waste Isolation Pilot Plant (WIPP). Relative permeability characteristic curves are necessary for WIPP Performance Assessment (PA) predictions of the potential for flow of waste-generated gas from the repository and brine flow into repository. This report follows Christiansen and Howarth (1995), a comprehensive literature review of methods for measuring relative permeability. It focuses on unsteady-state experiments and describes five methods for obtaining relative permeability relationships from unsteady-state experiments. Unsteady-state experimental methods were recommended for relative permeability measurements of low-permeability anhydrite rock samples form the Salado Formation because these tests produce accurate relative permeability information and take significantly less time to complete than steady-state tests. Five methods for obtaining relative permeability relationships from unsteady-state experiments are described: the Welge method, the Johnson-Bossler-Naumann method, the Jones-Roszelle method, the Ramakrishnan-Cappiello method, and the Hagoort method. A summary, an example of the calculations, and a theoretical justification are provided for each of the five methods. Displacements in porous media are numerically simulated for the calculation examples. The simulated product data were processed using the methods, and the relative permeabilities obtained were compared with those input to the numerical model. A variety of operating conditions were simulated to show sensitivity of production behavior to rock-fluid properties.

  20. Photophysical properties of 1,8-naphthalic anhydride in aprotic solvents: An electron acceptor in excited state

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Sujay; Biswas, Subhanip; Mondal, Mousumi; Basu, Samita, E-mail: samita.basu@saha.ac.in

    2014-01-15

    1,8-Naphthalic anhydride (NAN) has long been known as an intermediate for the synthesis of 1,8-naphthalimide derivatives with diverse applications. Uses of NAN for other purposes are restricted because it hydrolyzes in water and other protic solvents. In the current work we have investigated the absorption, steady-state and time-resolved fluorescence spectroscopy of NAN in eight different aprotic solvents of varying polarity. The compound is found to have different quantum yields in all the solvents. Astoundingly, NAN shows minimal fluorescence yield in dimethyl sulphoxide and N,N-dimethylformamide which is found to originate from pure collisional quenching owing to proton affinity of the solvent. In aprotic solvents acetonitrile and ethyl acetate, fluorescence emission and lifetime of NAN are quenched on addition of aliphatic amines namely triethylamine (TEA), tri-N-butylamine (TBA) and diisopropylethylamine (DIEA). Laser flash photolysis experiments in acetonitrile solvent have been used to find out the transient intermediates, which depict the involvement of photo-induced electron transfer from the amines to NAN. Hence, NAN has the potential to act as an efficient photo-induced electron acceptor in aprotic medium. -- Highlights: • In aprotic solvents NAN absorbs with maximum around 330–340 nm. • NAN fluoresce in aprotic solvents with maximum around 345–395 nm. • NAN has negligibly poor fluorescence in DMSO and DMF. • Fluorescence of NAN in aprotic solvents is quenched by TEA, TBA and DIEA. • Photo-induced electron transfer from the amines to NAN is the reason for such interaction.